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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
OFFSET
0,12
LINKS
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
First differences of A010553.
Sequence in context: A227193 A287397 A364204 * A374065 A084440 A179287
KEYWORD
sign
AUTHOR
N. J. A. Sloane, Nov 12 2005
EXTENSIONS
Description clarified by Antti Karttunen, Oct 07 2017
STATUS
approved