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A111407 a(n) = f(f(n+1)) - f(f(n)), where f(0) = 0 and f(m) = tau(m) = A000005(m) for m > 0. 2
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 (list; graph; refs; listen; history; text; internal format)
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.

Sequence in context: A179769 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

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Last modified July 20 15:59 EDT 2019. Contains 325185 sequences. (Running on oeis4.)