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a(n) = Sum_{d|n, d=3 mod 4} d^3.
2

%I #14 Oct 13 2024 18:58:36

%S 0,0,27,0,0,27,343,0,27,0,1331,27,0,343,3402,0,0,27,6859,0,370,1331,

%T 12167,27,0,0,19710,343,0,3402,29791,0,1358,0,43218,27,0,6859,59346,0,

%U 0,370,79507,1331,3402,12167,103823,27,343,0,132678,0,0

%N a(n) = Sum_{d|n, d=3 mod 4} d^3.

%H Seiichi Manyama, <a href="/A050454/b050454.txt">Table of n, a(n) for n = 1..10000</a>

%p A050454 := proc(n) local a,d; a := 0 ; for d in numtheory[divisors](n) do if d mod 4 = 3 then a := a+d^3 ; end if; end do; a ; end proc:

%p seq(A050454(n),n=1..100) ; # _R. J. Mathar_, Jan 07 2011

%t a[n_] := DivisorSum[n, #^3 &, Mod[#, 4]==3 &]; Array[a, 30] (* _Amiram Eldar_, Dec 06 2018 *)

%t Table[Total[Select[Divisors[n],Mod[#,4]==3&]^3],{n,80}] (* _Harvey P. Dale_, Oct 13 2024 *)

%K nonn

%O 1,3

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