A060778 - OEIS

A060778

a(n) = gcd(A000005(n+1), A000005(n)).

1, 2, 1, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 4, 1, 1, 2, 2, 2, 2, 4, 2, 2, 1, 1, 4, 2, 2, 2, 2, 2, 2, 4, 4, 1, 1, 2, 4, 4, 2, 2, 2, 2, 6, 2, 2, 2, 1, 3, 2, 2, 2, 2, 4, 4, 4, 4, 2, 2, 2, 2, 2, 1, 1, 4, 2, 2, 2, 4, 2, 2, 2, 2, 2, 6, 2, 4, 2, 2, 5, 1, 2, 2, 4, 4, 4, 4, 2, 2, 4, 2, 2, 4, 4, 4, 2, 2, 6, 3, 1, 2, 2, 2, 8, 4

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Harry J. Smith, Table of n, a(n) for n=1..1000

MATHEMATICA

GCD@@@Partition[DivisorSigma[0, Range[110]], 2, 1] (* Harvey P. Dale, May 27 2014 *)

PROG

(PARI) { t=1; for (n=1, 1000, d=numdiv(n+1); write("b060778.txt", n, " ", gcd(d, t)); t=d; ) } \\ Harry J. Smith, Jul 11 2009

(PARI) a(n) = gcd(numdiv(n), numdiv(n+1)); \\ Michel Marcus, Jan 12 2018

(Python)

from math import gcd