A111407 a(n) = f(f(n+1)) - f(f(n)), where f(0) = 0 and f(m) = tau(m) = A000005(m) for m > 0.

1, 1, 0, 0, 0, 1, -1, 1, -1, 1, -1, 2, -2, 1, 0, -1, 0, 2, -2, 2, -1, 0, -1, 2, -2, 1, 0, 1, -2, 2, -2, 2, -1, 0, 0, 0, -1, 1, 0, 1, -2, 2, -2, 2, 0, -1, -1, 2, -2, 2, -1, 1, -2, 2, -1, 1, -1, 0, -1, 4, -4, 1, 1, -2, 1, 1, -2, 2, -1, 1, -2, 4, -4, 1, 1, 0, -1, 1, -2, 2, -2, 1, -1, 4, -3, 0, 0, 1, -2, 4, -3, 1, -1, 0, 0, 3, -4, 2, 0, -1, -1

Offset

0,12

Links

Antti Karttunen, Table of n, a(n) for n = 0..20000

Prog

(PARI)
f = numdiv;
a(n) = f(f(n+1)) - f(f(n));
concat([1], vector(166, n, a(n))) \\ Joerg Arndt, Jul 06 2013
(PARI)
f(n) = if(!n, n, numdiv(n));
A111407(n) = f(f(n+1)) - f(f(n)); \\ Antti Karttunen, Oct 07 2017

Crossrefs

Cf. A000005, A111405.

First differences of A010553.

Sequence in context: A340594 A227193 A287397 * A084440 A179287 A016372

Adjacent sequences: A111404 A111405 A111406 * A111408 A111409 A111410

Keyword

sign

Author

N. J. A. Sloane, Nov 12 2005

Extensions

Description clarified by Antti Karttunen, Oct 07 2017

Status

approved