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 A282585 Number of ways to write n as an ordered sum of 3 squarefree palindromes (A071251). 2
 0, 0, 0, 1, 3, 6, 7, 9, 12, 19, 21, 21, 18, 24, 27, 28, 18, 18, 19, 24, 15, 10, 6, 12, 12, 12, 9, 9, 12, 15, 18, 12, 9, 7, 15, 15, 15, 9, 12, 15, 18, 18, 12, 9, 9, 18, 15, 12, 0, 9, 9, 9, 0, 0, 0, 6, 6, 9, 12, 9, 12, 15, 18, 18, 12, 9, 13, 18, 18, 18, 9, 15, 18, 21, 18, 12, 9, 15, 21, 21, 21, 9, 18, 21, 24, 18 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS Every number can be written as the sum of 3 palindromes (see A261132 and A261422). Conjecture: a(n) > 0 for any sufficiently large n. Additional conjecture: every number > 3 can be written as the sum of 4 squarefree palindromes. LINKS Ilya Gutkovskiy, Extended graphical example Ilya Gutkovskiy, Extended graphical example for additional conjecture Eric Weisstein's World of Mathematics, Palindromic Number Eric Weisstein's World of Mathematics, Squarefree FORMULA G.f.: (Sum_{k>=1} x^A071251(k))^3. EXAMPLE a(22) = 6 because we have [11, 6, 5], [11, 5, 6] [6, 11, 5], [6, 5, 11], [5, 11, 6] and [5, 6, 11]. MATHEMATICA nmax = 85; CoefficientList[Series[Sum[Boole[SquareFreeQ[k] && PalindromeQ[k]] x^k, {k, 1, nmax}]^3, {x, 0, nmax}], x] CROSSREFS Cf. A002113, A005117, A035137, A071251, A091580, A091581, A260254, A261131, A261132, A261422, A280210, A282584. Sequence in context: A231664 A087916 A296693 * A280210 A023982 A189092 Adjacent sequences:  A282582 A282583 A282584 * A282586 A282587 A282588 KEYWORD nonn AUTHOR Ilya Gutkovskiy, Feb 19 2017 STATUS approved

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Last modified October 17 07:05 EDT 2018. Contains 316276 sequences. (Running on oeis4.)