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A228004
Prime powers p^m with m >= 2 which are not the sum of consecutive cubes.
1
4, 16, 25, 32, 49, 81, 121, 128, 169, 243, 256, 289, 361, 529, 625, 841, 961, 1024, 1369, 1681, 1849, 2048, 2187, 2209, 2401, 2809, 3125, 3481, 3721, 4489, 5041, 5329, 6241, 6561, 6889, 7921, 8192, 9409, 10201, 10609, 11449, 11881, 12769, 14641, 16129
OFFSET
1,1
LINKS
G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 97
EXAMPLE
9 is not in the sequence since it is equal to 1^3 + 2^3.
PROG
(Magma) lst:=[]; r:=26; c:=r^3; for n in [2..r] do for m in [n-1..0 by -1] do s:=((n^2+n)^2-(m^2+m)^2)/4; if s gt c then break; end if; if not s in lst then Append(~lst, s); end if; end for; end for; lst:=Sort(lst); [p: p in [2..c] | not IsPrime(p) and IsPrimePower(p) and not p in lst];
CROSSREFS
Sequence in context: A239522 A281990 A103052 * A269157 A343726 A202303
KEYWORD
nonn
AUTHOR
STATUS
approved