A341206 Number of ways to write n as an ordered sum of 9 nonzero decimal palindromes.
1, 9, 45, 165, 495, 1287, 3003, 6435, 12870, 24301, 43686, 75249, 124809, 200115, 311157, 470415, 693000, 996633, 1401436, 1929465, 2603979, 3448440, 4485267, 5734395, 7211718, 8927523, 10885050, 13079257, 15496065, 18112050, 20894757, 23803659, 26791749, 29807697, 32798448
Offset: 9
Links
- Alois P. Heinz, Table of n, a(n) for n = 9..10000
Crossrefs
Programs
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Maple
p:= proc(n) option remember; local i, s; s:= ""||n; for i to iquo(length(s), 2) do if s[i]<>s[-i] then return false fi od; true end: b:= proc(n, t) option remember; `if`(n=0, `if`(t=0, 1, 0), `if`(t<1, 0, add(`if`(p(j), b(n-j, t-1), 0), j=1..n))) end: a:= n-> b(n, 9): seq(a(n), n=9..43); # Alois P. Heinz, Feb 07 2021
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Mathematica
nmax = 43; CoefficientList[Series[Sum[Boole[PalindromeQ[k]] x^k, {k, 1, nmax}]^9, {x, 0, nmax}], x] // Drop[#, 9] &