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A130638
a(n) = 1 iff d(n) = d(n+1), otherwise a(n)=0, where d(n) is the number of divisors of n, A000005.
2
0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0
OFFSET
1,1
MATHEMATICA
Table[If[Length[Divisors[n]] == Length[Divisors[n + 1]], 1, 0], {n, 1, 80}] (* Stefan Steinerberger, Aug 12 2007 *)
PROG
(PARI) A130638(n) = (numdiv(n)==numdiv(n+1)); \\ Antti Karttunen, Oct 04 2017
CROSSREFS
Characteristic function of A005237.
Cf. A000005.
Sequence in context: A216284 A360109 A355452 * A030217 A030215 A283020
KEYWORD
nonn
AUTHOR
Giovanni Teofilatto, Aug 11 2007
EXTENSIONS
Corrected and extended by Stefan Steinerberger, Aug 12 2007
More terms (up to a(105)) from Antti Karttunen, Oct 04 2017
STATUS
approved