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A070010 GCD of consecutive values of sum-of-proper divisors. 1
1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 11, 1, 1, 1, 6, 2, 1, 1, 1, 1, 1, 1, 1, 5, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 4, 1, 1, 1, 23, 1, 1, 1, 1, 3, 1, 1, 5, 25, 1, 1, 1, 1, 3, 1, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,9

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = gcd(A001065(n+1), A001065(n)).

MATHEMATICA

GCD[DivisorSigma[1, n+1]-(n+1), DivisorSigma[1, n]-n]

PROG

(PARI)

A001065(n) = (sigma(n) - n);

A070010(n) = gcd(A001065(n), A001065(1+n)); \\ Antti Karttunen, Oct 05 2017

CROSSREFS

Cf. A000203, A001065; GCD of various consecutive function values: A048586, A057467, A058515, A060778, A060780, A069896.

Sequence in context: A184101 A164561 A178764 * A293768 A046564 A046592

Adjacent sequences:  A070007 A070008 A070009 * A070011 A070012 A070013

KEYWORD

nonn

AUTHOR

Labos Elemer, Apr 11 2002

STATUS

approved

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Last modified October 15 21:17 EDT 2019. Contains 328038 sequences. (Running on oeis4.)