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A261906 Numbers that are the sum of two nonzero palindromes. 7

%I

%S 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,22,23,24,25,26,27,

%T 28,29,30,31,33,34,35,36,37,38,39,40,41,42,44,45,46,47,48,49,50,51,52,

%U 53,55,56,57,58,59,60,61,62,63,64,66,67,68,69,70,71,72,73,74,75,77,78,79,80,81,82,83,84,85,86,88,89,90,91,92,93,94,95,96,97,99,100,101,102,103,104,105,106,107,108,109,110,112,113,114,115,116,117,118,119,120

%N Numbers that are the sum of two nonzero palindromes.

%C More than the usual number of terms are shown in order to distinguish this from A260255.

%e 22 is a member because it is the sum of two palindromes, 11+11 (not because it is a palindrome in its own right).

%e 111 is not the sum of two nonzero palindromes, so appears in A260255 but not here. See A213879 for further differences between the two sequences.

%p # Sums of two nonzero pals:

%p # bP has a list of palindromes starting at 0.

%p a2:={}; M:=60; M2:=bP[M];

%p for i from 2 to M do

%p for j from i to M do

%p k:=bP[i]+bP[j];

%p if k <= M2 then a2:={op(a2),k}; fi;

%p od: od:

%p b2:=sort(convert(a2,list));

%Y Cf. A002113, A260255, A213879.

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Sep 09 2015

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Last modified April 6 21:24 EDT 2020. Contains 333286 sequences. (Running on oeis4.)