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

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
from sympy import divisor_count
def A060778(n): return gcd(divisor_count(n+1), divisor_count(n)) # Chai Wah Wu, Aug 12 2023

Crossrefs

Cf. A000005, A057921, A058074.

Sequence in context: A213911 A081355 A223708 * A096492 A343856 A053874

Adjacent sequences: A060775 A060776 A060777 * A060779 A060780 A060781

Keyword

nonn

Author

Labos Elemer, Apr 26 2001

Status

approved