The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A238002

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

A238002

Count with multiplicity of prime factors of n in (n - 1)!.
(history; published version)

#29 by Harvey P. Dale at Sat Jan 23 16:12:05 EST 2016

STATUS

editing

approved

#28 by Harvey P. Dale at Sat Jan 23 16:12:00 EST 2016

MATHEMATICA

cmpf[n_]:=Count[Flatten[Table[#[[1]], {#[[2]]}]&/@FactorInteger[ (n-1)!]], _?( MemberQ[Transpose[FactorInteger[n]][[1]], #]&)]; Array[cmpf, 80] (* Harvey P. Dale, Jan 23 2016 *)

STATUS

approved

editing

#27 by Joerg Arndt at Thu Mar 20 03:45:53 EDT 2014

STATUS

proposed

approved

#26 by Alonso del Arte at Wed Mar 19 22:35:31 EDT 2014

STATUS

editing

proposed

#25 by Alonso del Arte at Wed Mar 19 22:35:18 EDT 2014

FORMULA

a(2n) > a(2n - + 1) for all n > 12.

STATUS

approved

editing

#24 by Ralf Stephan at Mon Mar 17 12:30:37 EDT 2014

STATUS

reviewed

approved

#23 by Alois P. Heinz at Mon Mar 17 12:28:27 EDT 2014

STATUS

proposed

reviewed

#22 by Alois P. Heinz at Mon Mar 17 12:28:20 EDT 2014

STATUS

editing

proposed

#21 by Alois P. Heinz at Mon Mar 17 12:27:25 EDT 2014

LINKS

Alois P. Heinz, <a href="/A238002/b238002.txt">Table of n, a(n) for n = 2..10000</a>

#20 by Alois P. Heinz at Mon Mar 17 09:22:04 EDT 2014

MAPLE

with(numtheory):

a:= n-> add(add(`if`(i[1] in factorset(n), i[2], 0),

i=ifactors(j)[2]), j=1..n-1):

seq(a(n), n=2..100); # Alois P. Heinz, Mar 17 2014

STATUS

proposed

editing

Discussion

Mon Mar 17

09:24

Alois P. Heinz: There is no need to compute factorial(n-1).  It is sufficient to sum over the factors of factorial(n-1), i.e. j=1,...,n-1.