A050448 - OEIS

%I #20 Jul 08 2023 08:05:42

%S 1,1,1,1,626,1,1,1,6562,626,1,1,28562,1,626,1,83522,6562,1,626,194482,

%T 1,1,1,391251,28562,6562,1,707282,626,1,1,1185922,83522,626,6562,

%U 1874162,1,28562,626,2825762,194482,1,1,4107812,1,1,1

%N a(n) = Sum_{d|n, d==1 (mod 4)} d^4.

%H Seiichi Manyama, <a href="/A050448/b050448.txt">Table of n, a(n) for n = 1..10000</a>

%t a[n_] := DivisorSum[n, #^4 &, Mod[#, 4] == 1 &]; Array[a, 50] (* _Amiram Eldar_, Jul 08 2023 *)

%o (PARI) a(n) = sumdiv(n, d, if ((d%4)==1, d^4)); \\ _Michel Marcus_, Aug 16 2021

%Y Cf. A001159, A050449, A050450, A050451.

%K nonn

%O 1,5

%A _N. J. A. Sloane_, Dec 23 1999

%E Offset corrected by _Sean A. Irvine_, Aug 15 2021