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Number of ways to write n as an ordered sum of 3 nonzero decimal palindromes.
9

%I #7 Feb 07 2021 13:10:15

%S 1,3,6,10,15,21,28,36,45,52,60,66,70,72,72,70,66,60,55,45,39,34,30,27,

%T 25,24,24,24,27,27,25,27,27,27,27,27,27,27,27,30,27,27,30,30,30,30,30,

%U 30,30,30,33,27,30,33,33,33,33,33,33,33,33,36,27,34,36,36,36,36

%N Number of ways to write n as an ordered sum of 3 nonzero decimal palindromes.

%H Alois P. Heinz, <a href="/A341192/b341192.txt">Table of n, a(n) for n = 3..20000</a>

%t nmax = 70; CoefficientList[Series[Sum[Boole[PalindromeQ[k]] x^k, {k, 1, nmax}]^3, {x, 0, nmax}], x] // Drop[#, 3] &

%Y Cf. A002113, A136522, A261131, A261132, A261422, A341156, A341191, A341193.

%K nonn,base

%O 3,2

%A _Ilya Gutkovskiy_, Feb 06 2021