OFFSET
0,8
COMMENTS
Is there k which satisfies a(n) > 0 for all n > k?
LINKS
Ilya Gutkovskiy, Extended graphical example
Eric Weisstein's World of Mathematics, Prime Power
Eric Weisstein's World of Mathematics, Palindromic Number
FORMULA
G.f.: (Sum_{k>=1} x^A084092(k))^6.
EXAMPLE
a(7) = 6 because we have:
[2, 1, 1, 1, 1, 1]
[1, 2, 1, 1, 1, 1]
[1, 1, 2, 1, 1, 1]
[1, 1, 1, 2, 1, 1]
[1, 1, 1, 1, 2, 1]
[1, 1, 1, 1, 1, 2]
MATHEMATICA
nmax = 55; CoefficientList[Series[(x + Sum[Boole[PrimePowerQ[k] && PalindromeQ[k]] x^k, {k, 1, nmax}])^6, {x, 0, nmax}], x]
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Ilya Gutkovskiy, Feb 22 2017
STATUS
approved