The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A058317

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
Showing entries 1-10 | older changes

A058317

Number of neutrons in atoms of the n-th element of the periodic table (for the most abundant isotope).
(history; published version)

#31 by Alois P. Heinz at Tue Jul 02 20:32:56 EDT 2024

MAPLE

V:=array(1..71):V[18]:=-2:V[27]:=-1:V[52]:=5:V[53]:=-2:

U:=convert(44091781633204996400746822649066693026224784537, base, 5):

for i from 1 to 17 do: V[i]:=U[i]:od:

for j from 19 to 26 do: V[j]:=U[j-1]:od:

for k from 28 to 51 do: V[k]:=U[k-2]:od:

for l from 54 to 70 do: V[l]:=U[l-3]:od:

s:=0:printf(`%d, `, 0):

for q from 1 to 70 do:

s:=s+V[q]: printf(`%d, `, s):

od:# Michel Lagneau, Jul 01 2024

KEYWORD

nonn,fini,changed

STATUS

editing

approved

#30 by Alois P. Heinz at Tue Jul 02 20:32:50 EDT 2024

STATUS

proposed

editing

#29 by Michel Lagneau at Tue Jul 02 00:57:24 EDT 2024

STATUS

editing

proposed

Discussion

Tue Jul 02

05:46

Kevin Ryde: There's no programs for this type of sequence because there's no mathematical definition.  Ready for a revert, yes?

09:35

Michel Lagneau: I agree with you, indeed there is no program for this type of sequence because there is no mathematical definition.
As the sequence is finished, I tried to find a method to reconstruct the sequence from a number and information extracted from the sequence. There are no mathematical laws, and there is no formula.
Thanks !

15:32

Alois P. Heinz: the sequence is finite but it is not full ... meaning: there exist terms that are not in the data section and not in a b-file ...

20:32

Alois P. Heinz: Ready for a revert, yes!

#28 by Michel Lagneau at Tue Jul 02 00:52:53 EDT 2024

MAPLE

V:=array(1..7071):V[18]:=-2:V[27]:=-1:V[52]:=5:V[53]:=-2:

Discussion

Tue Jul 02

00:55

Michel Lagneau: Program corrected with V:=array(1..71):
From the integer N = 44091781633204996400746822649066693026224784537 and V[18]:=-2:V[27]:=-1:V[52]:=5:V[53]:=-2 which contains 47 + 4 = 51 elements we calculate exactly the 71 elements of a(n).

#27 by Alois P. Heinz at Mon Jul 01 19:47:24 EDT 2024

STATUS

proposed

editing

Discussion

Mon Jul 01

19:49

Alois P. Heinz: the program is useless ... unable to compute more than the hard-wired terms ...

#26 by Michel Marcus at Mon Jul 01 12:23:52 EDT 2024

STATUS

editing

proposed

Discussion

Mon Jul 01

19:47

Alois P. Heinz: the program is designed to reproduce the terms in data, but its size is larger than the list of terms.  The program is unable to compute the next term ... 
Error, 1st index, 71, larger than upper array bound 70

#25 by Michel Marcus at Mon Jul 01 12:23:46 EDT 2024

MAPLE

U:=convert(44091781633204996400746822649066693026224784537, base, 5):

, base, 5):

STATUS

proposed

editing

#24 by Michel Lagneau at Mon Jul 01 11:52:50 EDT 2024

STATUS

editing

proposed

#23 by Michel Lagneau at Mon Jul 01 11:51:36 EDT 2024

MAPLE

V:=array(1..70):V[18]:=-2:V[27]:=-1:V[52]:=5:V[53]:=-2:

U:=convert(44091781633204996400746822649066693026224784537

, base, 5):

for i from 1 to 17 do: V[i]:=U[i]:od:

for j from 19 to 26 do: V[j]:=U[j-1]:od:

for k from 28 to 51 do: V[k]:=U[k-2]:od:

for l from 54 to 70 do: V[l]:=U[l-3]:od:

s:=0:printf(`%d, `, 0):

for q from 1 to 70 do:

s:=s+V[q]: printf(`%d, `, s):

od:# Michel Lagneau, Jul 01 2024

STATUS

approved

editing

Discussion

Mon Jul 01

11:52

Michel Lagneau: From the integer N = 44091781633204996400746822649066693026224784537 which contains 47 digits we calculate exactly the 71 elements of a(n) after conversion of N to base 5. The integer N converted to base 5 are the elements {delta(n)} of first differences of the sequence {a(n)}. We perform the transformation {delta(n)} -> {c(n)} minus {negative numbers} and {5}. Then we calculate N=sum('c[i]*5 ^(i-1)', 'i'=1..68) where 68 = 71 - 3. Then we perform the last transformation {c(n)} -> {delta(n)} by insertion of the primitive negative elements and the integer 5. Finally we calculate the sequence a(n) from the partial sums of {delta(n)}.
Why base 5, because it gives N as small as possible from c(n).

#22 by Michel Marcus at Tue Sep 28 06:17:11 EDT 2021

STATUS

reviewed

approved