A015999 a(n) = (tau(n^5) + 4)/5.

1, 2, 2, 3, 2, 8, 2, 4, 3, 8, 2, 14, 2, 8, 8, 5, 2, 14, 2, 14, 8, 8, 2, 20, 3, 8, 4, 14, 2, 44, 2, 6, 8, 8, 8, 25, 2, 8, 8, 20, 2, 44, 2, 14, 14, 8, 2, 26, 3, 14, 8, 14, 2, 20, 8, 20, 8, 8, 2, 80, 2, 8, 14, 7, 8, 44, 2, 14, 8, 44, 2, 36, 2, 8, 14, 14, 8, 44, 2, 26, 5, 8, 2, 80, 8, 8

Offset: 1

Author

Robert G. Wilson v

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A000005, A018892, A015995, A015996, A016001, A016002, A016003, A016005, A016006, A016007, A016008, A016012.

Programs

Maple

with(numtheory): A015999:=n->(tau(n^5)+4)/5: seq(A015999(n), n=1..80); # Wesley Ivan Hurt, Apr 10 2015

Mathematica

(DivisorSigma[0, Range[80]^5]+4)/5 (* Wesley Ivan Hurt, Apr 10 2015 *)

PARI

A015999(n) = (numdiv(n^5)+4)/5;
for(n=1, 10000, write("b015999.txt", n, " ", A015999(n)));
\\ Antti Karttunen, Jan 17 2017

Python

from sympy import divisor_count
def a(n): return (divisor_count(n**5) + 4)//5
print([a(n) for n in range(1, 101)]) # Indranil Ghosh, Apr 14 2017

Extensions

Definition corrected by Vladeta Jovovic, Sep 03 2005