A179930 a(n) = gcd(n, A001157(n)).

1, 1, 1, 1, 1, 2, 1, 1, 1, 10, 1, 6, 1, 2, 5, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 14, 1, 10, 1, 1, 1, 2, 5, 3, 1, 2, 1, 10, 1, 2, 1, 2, 1, 2, 1, 2, 1, 5, 1, 2, 1, 2, 1, 2, 1, 2, 1, 60, 1, 2, 7, 1, 65, 2, 1, 2, 1, 10, 1, 1, 1, 2, 15, 2, 1, 2, 1, 2, 1, 2, 1, 84, 5, 2, 1, 2, 1, 10, 1, 2, 1, 2, 1, 6

Offset: 1

Author

N. J. A. Sloane, Jul 09 2011, following a suggestion from R. J. Mathar

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384

Crossrefs

Cf. A001157, A082063, A082069, A179931, A009194.

Programs

Maple

A179930 := proc(n) igcd( n, numtheory[sigma][2](n)) ; end proc:
seq(A179930(n),n=1..100) ;

Mathematica

Array[GCD[#, DivisorSigma[2, #]] &, 96] (* Michael De Vlieger, Nov 03 2017 *)

PARI

A179930(n) = gcd(n,sigma(n,2)); \\ Antti Karttunen, Nov 03 2017

Formula

A006530(a(n)) = A082063(n). - Reinhard Zumkeller, Jul 10 2011

A020639(a(n)) = A082069(n). - Antti Karttunen, Nov 03 2017