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 A248334 The subsequence of A246885 having even values. 1
 0, 2, 4, 6, 16, 20, 32, 34, 48, 54, 58, 86, 108, 110, 124, 128, 132, 160, 162, 236, 250, 254, 256, 258, 272, 282, 310, 358, 384, 432, 436, 464, 500, 502, 506, 516, 540, 554, 628, 686, 688, 690, 718, 750, 794, 864, 866, 880, 918, 932, 942, 992, 1024, 1028, 1056 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Let f(x)=Sum(x^i^3), then 1/f(x) has coefficients given in A246885. The subsequence of A246885 having even values is A248334. This is the same as the numbers that can be written in an odd number of ways as a sum 2r^3 + 4s^3, where r and s are nonnegative integers. LINKS Alois P. Heinz, Table of n, a(n) for n = 1..10000 Joshua N. Cooper, Dennis Eichhorn, Kevin O'Bryant, Reciprocals of Binary Power Series, arXiv:math/0506496 [math.NT], 2005. MAPLE b:= proc(n) option remember; irem(`if`(n=0, 1,       `if`(n<0, 0, add(b(n-i^3), i=1..iroot(n, 3)))), 2)     end: a:= proc(n) option remember; local k; for k from 2+       `if`(n=1, -2, a(n-1)) by 2 while b(k)=0 do od; k     end: seq(a(n), n=1..80);  # Alois P. Heinz, Dec 28 2014 MATHEMATICA InverseOfCubes[m_]:=Module[{V}, V=1; Do[V[i]=0, {i, 1, m}]; Reap[Sow; Do[If[OddQ[Sum[V[counter-i^3], {i, 1, counter^(1/3)}]], V[counter]=1; Sow[counter]], {counter, 1, m}]][[2, 1]]] inv=InverseOfCubes; Select[inv, EvenQ] (* This program adapted from code written by Kevin O'Bryant *) CROSSREFS Sequence in context: A069654 A000068 A067662 * A001774 A053285 A286850 Adjacent sequences:  A248331 A248332 A248333 * A248335 A248336 A248337 KEYWORD nonn AUTHOR David S. Newman, Oct 04 2014 EXTENSIONS More terms from Alois P. Heinz, Dec 28 2014 STATUS approved

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Last modified November 13 17:34 EST 2019. Contains 329106 sequences. (Running on oeis4.)