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A009205 a(n) = gcd(d(n), sigma(n)). 12
1, 1, 2, 1, 2, 4, 2, 1, 1, 2, 2, 2, 2, 4, 4, 1, 2, 3, 2, 6, 4, 4, 2, 4, 1, 2, 4, 2, 2, 8, 2, 3, 4, 2, 4, 1, 2, 4, 4, 2, 2, 8, 2, 6, 6, 4, 2, 2, 3, 3, 4, 2, 2, 8, 4, 8, 4, 2, 2, 12, 2, 4, 2, 1, 4, 8, 2, 6, 4, 8, 2, 3, 2, 2, 2, 2, 4, 8, 2, 2, 1, 2, 2, 4, 4, 4, 4, 4, 2, 6, 4, 6, 4, 4, 4, 12, 2, 3, 6, 1, 2, 8, 2, 2, 8, 2, 2, 4, 2, 8, 4, 2, 2, 8, 4, 6, 2, 4, 4, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

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

MATHEMATICA

Table[GCD[DivisorSigma[0, n], DivisorSigma[1, n]], {n, 120}] (* Harvey P. Dale, Dec 05 2017 *)

PROG

(PARI) A009205(n) = gcd(numdiv(n), sigma(n)); \\ Antti Karttunen, May 22 2017

CROSSREFS

Cf. A000005, A000203, A009191, A009194, A087801, A286360.

Sequence in context: A121439 A307448 A305350 * A086754 A120880 A059151

Adjacent sequences:  A009202 A009203 A009204 * A009206 A009207 A009208

KEYWORD

nonn

AUTHOR

David W. Wilson

EXTENSIONS

Data section extended to 120 terms by Antti Karttunen, May 22 2017

STATUS

approved

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Last modified November 22 08:46 EST 2019. Contains 329389 sequences. (Running on oeis4.)