A015996 - OEIS

%I #17 Jan 17 2017 12:32:21

%S 1,2,2,3,2,7,2,4,3,7,2,12,2,7,7,5,2,12,2,12,7,7,2,17,3,7,4,12,2,32,2,

%T 6,7,7,7,21,2,7,7,17,2,32,2,12,12,7,2,22,3,12,7,12,2,17,7,17,7,7,2,57,

%U 2,7,12,7,7,32,2,12,7,32,2,30,2,7,12,12,7,32,2,22,5,7,2,57,7,7

%N (tau(n^4) + 3)/4, where tau = A000005.

%C If n is prime, a(n) = 2 since a(p) = (tau(p^4)+3)/4 = (5+3)/4 = 2. - _Wesley Ivan Hurt_, Nov 16 2013

%H Antti Karttunen, <a href="/A015996/b015996.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = (A000005(n^4) + 3)/4.

%p A015996 := proc(n)

%p         (numtheory[tau](n^4)+3)/4 ;

%p end proc; # _R. J. Mathar_, May 09 2013

%t Table[(DivisorSigma[0, n^4] + 3)/4, {n, 100}] (* _Wesley Ivan Hurt_, Nov 16 2013 *)

%o (PARI)

%o A015996(n) = (numdiv(n^4)+3)/4;

%o for(n=1, 10000, write("b015996.txt", n, " ", A015996(n)));

%o \\ _Antti Karttunen_, Jan 17 2017

%Y Cf. A000005, A018892, A015995, A015999, A016001, A016002, A016003, A016005, A016006, A016007, A016008, A016009, A016012, A016020.

%K nonn

%O 1,2

%A _Robert G. Wilson v_

%E Definition corrected by Vladeta Jovovic, Sep 03 2005