A171937 Forward van Eck transform of A000005.

0, 1, 2, 5, 2, 2, 4, 2, 16, 4, 2, 6, 4, 1, 6, 65, 2, 2, 4, 8, 1, 4, 6, 6, 24, 1, 6, 4, 2, 10, 6, 12, 1, 1, 3, 64, 4, 1, 7, 2, 2, 12, 4, 1, 5, 5, 6, 32, 72, 2, 4, 11, 6, 2, 2, 10, 1, 4, 2, 12, 6, 3, 5, 665, 4, 4, 4, 7, 5, 8, 2, 12, 6, 3, 1, 16, 5, 10, 4, 32, 544, 3, 6, 6, 1, 1, 4, 14, 8, 6, 2, 6, 1, 1, 11

Offset

1,3

Comments

Least positive k such that d(n) = d(n+k), or 0 if no such k exists (d = A000005). - Altug Alkan, Jul 29 2016

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10001

N. J. A. Sloane, Transforms

Formula

a(n) = A079427(n) - n. - Ridouane Oudra, Sep 14 2021

Mathematica

{0}~Join~Array[Block[{k = 1}, While[DivisorSigma[0, #] != DivisorSigma[0, # + k], k++]; k] &, 94, 2] (* Michael De Vlieger, Aug 19 2021 *)

Prog

(PARI) a(n) = if (n==1, 0, my(m=1, nd=numdiv(n)); while(numdiv(n+m) != nd, m++); m); \\ Michel Marcus, Sep 14 2021

Crossrefs

Cf. A000005, A171936.

Cf. A079427.

Sequence in context: A286664 A306541 A242242 * A065291 A065267 A273990

Adjacent sequences: A171934 A171935 A171936 * A171938 A171939 A171940

Keyword

nonn

Author

N. J. A. Sloane, Oct 24 2010

Status

approved