A377474 - OEIS

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A377474

Indices where new terms arise among first differences of Colombian or self numbers (A377472).

1, 5, 103, 984, 9785, 97786, 977787, 9777788

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

See A377473 for the distinct values of the first differences in the order they appear for the first time.

LINKS

Table of n, a(n) for n=1..8.

FORMULA

a(n+1) = a(n) + 88*10^(n-1) + 1 for n = 3, 4, ..., 7 at least.

EXAMPLE

The first value, A377472(1) = 2, appears obviously at index a(1) = 1.

The next three values are the same, but at index a(2) = 5 we have a new, distinct value A377472(5) = 11 = A377423(2).

The next distinct value is A377472(103) = 15 = A377423(3), so a(3) = 103.

Then the next new value is A377472(984) = 28 = A377423(4), so a(4) = 984.

The next new value is A377472(9785) = 41 = A377423(5), so a(5) = 9785.

Then, at n = 97786 = a(6), we have A377472(n) = 54 = A377423(6).

Only at n = 977787 = a(7), we have a new value, A377472(n) = 67 = A377423(7).

At n = 9777788 = a(8), we have the next new value, A377472(n) = 80 = A377423(8).

PROG

(PARI) A377473_upto(N=9, show=1)={my(o, c, d, L=List()); for(n=1+o=1, oo, is_A003052(n)||next; c++; if(!setsearch(L, d=n-o), show && printf("%d, ", [c, d]); listput(L, c); #L<N||break); o=n); L}

CROSSREFS

Cf. A003052 (Colombian numbers), A377472 (1st differences of Colombian numbers), A377473 (distinct values of A377472 in order of appearance), A377423 (= A377473 - 1).

Sequence in context: A052138 A308459 A142418 * A159523 A172116 A007619

Adjacent sequences: A377469 A377472 A377473 * A377479 A377480 A377481

KEYWORD

nonn,more

AUTHOR

M. F. Hasler, Oct 30 2024

STATUS

approved