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A087801
Greatest common divisor of tau(n)+sigma(n) and tau(n)*sigma(n), where tau = A000005 and sigma = A000203.
2
1, 1, 2, 1, 4, 16, 2, 1, 1, 2, 2, 2, 4, 4, 4, 1, 4, 9, 2, 12, 4, 8, 2, 4, 1, 2, 4, 2, 4, 16, 2, 3, 4, 2, 4, 1, 4, 16, 4, 2, 4, 8, 2, 18, 12, 4, 2, 2, 3, 9, 4, 4, 4, 64, 4, 64, 4, 2, 2, 36, 4, 4, 2, 1, 8, 8, 2, 12, 4, 8, 2, 9, 4, 2, 2, 2, 4, 16, 2, 4, 1, 2, 2, 4, 16, 8, 4, 4, 4, 6, 4, 6, 4, 4, 4, 24
OFFSET
1,3
COMMENTS
a(n) = GCD(A007503(n), A064840(n)).
LINKS
MATHEMATICA
GCD[Total[#], Times@@#]&/@Table[{DivisorSigma[0, n], DivisorSigma[1, n]}, {n, 100}] (* Harvey P. Dale, Jul 17 2018 *)
PROG
(PARI) A087801(n) = gcd(sigma(n)+numdiv(n), sigma(n)*numdiv(n)); \\ Antti Karttunen, May 22 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 11 2003
STATUS
approved