This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A260254 #23 Aug 15 2015 08:04:18 %S A260254 1,1,2,2,3,3,4,4,5,5,5,5,5,4,4,3,3,2,2,1,1,0,2,1,1,1,1,1,1,1,1,1,0,2, %T A260254 1,1,1,1,1,1,1,1,1,0,3,1,1,1,1,1,1,1,1,1,0,3,1,1,1,1,1,1,1,1,1,0,4,1, %U A260254 1,1,1,1,1,1,1,1,0,4,1,1,1,1,1,1,1,1 %N A260254 Number of ways to write n as sum of two palindromes in decimal representation. %C A260254 a(A035137(n)) = 0; a(A260255(n)) > 0. %H A260254 Reinhard Zumkeller, <a href="/A260254/b260254.txt">Table of n, a(n) for n = 0..10000</a> %H A260254 Hugo Pfoertner, <a href="/A260254/a260254_2.png">Plot of first 10^6 terms</a> %H A260254 Hugo Pfoertner, <a href="/A260254/a260254_1.png">Plot of first 3*10^7 terms</a> %F A260254 a(n) = sum{A136522(n - A002113(k)): k = 1..floor(n/2)}. %e A260254 . n | a(n) | n | a(n) | %e A260254 . ----+------+-------------------------- ----+------+-------------- %e A260254 . 0 | 1 | 0 21 | 0 | ./. %e A260254 . 1 | 1 | 1 22 | 2 | 22, 11+11 %e A260254 . 2 | 2 | 2, 1+1 23 | 1 | 22+1 %e A260254 . 3 | 2 | 3, 2+1 24 | 1 | 22+2 %e A260254 . 4 | 3 | 4, 3+1, 2+2 25 | 1 | 22+3 %e A260254 . 5 | 3 | 5, 4+1, 3+2 26 | 1 | 22+4 %e A260254 . 6 | 4 | 6, 5+1, 4+2, 3+3 27 | 1 | 22+5 %e A260254 . 7 | 4 | 7, 6+1, 5+2, 4+3 28 | 1 | 22+6 %e A260254 . 8 | 5 | 8, 7+1, 6+2, 5+3, 4+4 29 | 1 | 22+7 %e A260254 . 9 | 5 | 9, 8+1, 7+2, 6+3, 5+4 30 | 1 | 22+8 %e A260254 . 10 | 5 | 9+1, 8+2, 7+3, 6+4, 5+5 31 | 1 | 22+9 %e A260254 . 11 | 5 | 11, 9+2, 8+3, 7+4, 6+5 32 | 0 | ./. %e A260254 . 12 | 5 | 11+1, 9+3, 8+4, 7+5, 6+6 33 | 2 | 33, 22+11 %e A260254 . 13 | 4 | 11+2, 9+4, 8+5, 7+6 34 | 1 | 33+1 %e A260254 . 14 | 4 | 11+3, 9+5, 8+6, 7+7 35 | 1 | 33+2 %e A260254 . 15 | 3 | 11+4, 9+6, 8+7 36 | 1 | 33+3 %e A260254 . 16 | 3 | 11+5, 9+7, 8+8 37 | 1 | 33+4 %e A260254 . 17 | 2 | 11+6, 9+8 38 | 1 | 33+5 %e A260254 . 18 | 2 | 11+7, 9+9 39 | 1 | 33+6 %e A260254 . 19 | 1 | 11+8 40 | 1 | 33+7 %e A260254 . 20 | 1 | 11+9 41 | 1 | 33+8 . %o A260254 (Haskell) %o A260254 a260254 n = sum $ map (a136522 . (n -)) $ %o A260254 takeWhile (<= n `div` 2) a002113_list %Y A260254 Cf. A002113, A136522, A035137, A260255. %K A260254 nonn,base,look %O A260254 0,3 %A A260254 _Reinhard Zumkeller_, Jul 21 2015