A181426 -id:A181426 - cp's OEIS frontend

A166604 Numbers k such that Sum_{i=1..k} i^4 divides Product_{i=1..k} i^4.

1, 31, 59, 94, 104, 122, 133, 181, 206, 223, 244, 248, 283, 298, 318, 342, 356, 401, 406, 421, 422, 439, 444, 449, 451, 469, 479, 493, 496, 507, 528, 532, 536, 541, 555, 597, 631, 637, 643, 668, 701, 706, 712, 717, 721, 722, 754, 762, 795, 797, 801, 815, 842

Offset: 1

Alexander Adamchuk, Oct 18 2009

nonn

			a(2) = A125314(4) = 31.

Harvey P. Dale, Table of n, a(n) for n = 1..3000

Cf. A125314, A166602, A060462, A166605, A166606, A166607, A166608, A166609, A166610, A181426, A334734.

k = s = 1; p = 1; lst = {}; While[k < 1000, If[ Mod[p, s] == 0, AppendTo[lst, k]]; k++; s = s + k^4; p = p*k^4]; lst (* Robert G. Wilson v, Nov 02 2009 *)
Module[{nn=1000,c},c=Range[nn]^4;Select[Range[nn],Divisible[Times@@ Take[ c,#], Total[Take[c,#]]]&]] (* Harvey P. Dale, Dec 18 2013 *)

a(15)-a(53) from Robert G. Wilson v, Nov 02 2009

A334734 Denominator of Sum_{k=1..n} k^4 / Product_{k=1..n} k^4.

Original entry on oeis.org

1, 16, 648, 55296, 207360000, 10749542400, 23044331520000, 220242357780480000, 5780040437590917120000, 3538800267912806400000000, 115398507336502660300800000000, 5264387585885382160794255360000000, 1835850718442886445597615718400000000

Offset: 1

Petros Hadjicostas, May 09 2020

			The first few fractions are 1, 17/16, 49/648, 59/55296, 979/207360000, 91/10749542400, 167/23044331520000, ... = A181426/A334734.

Cf. A166604, A181426 (numerators).

a(n) = denominator(sum(k=1, n, k^4)/prod(k=1, n, k^4)); \\ Michel Marcus, May 09 2020

cp's OEIS Frontend

A166604 Numbers k such that Sum_{i=1..k} i^4 divides Product_{i=1..k} i^4.

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