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A260254
Number of ways to write n as sum of two palindromes in decimal representation.
12
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, 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, 1, 1, 1, 1, 1, 1, 1, 1, 0, 4, 1, 1, 1, 1, 1, 1, 1, 1
OFFSET
0,3
COMMENTS
a(A035137(n)) = 0; a(A260255(n)) > 0.
LINKS
Hugo Pfoertner, Plot of first 10^6 terms
FORMULA
a(n) = sum{A136522(n - A002113(k)): k = 1..floor(n/2)}.
EXAMPLE
. n | a(n) | n | a(n) |
. ----+------+-------------------------- ----+------+--------------
. 0 | 1 | 0 21 | 0 | ./.
. 1 | 1 | 1 22 | 2 | 22, 11+11
. 2 | 2 | 2, 1+1 23 | 1 | 22+1
. 3 | 2 | 3, 2+1 24 | 1 | 22+2
. 4 | 3 | 4, 3+1, 2+2 25 | 1 | 22+3
. 5 | 3 | 5, 4+1, 3+2 26 | 1 | 22+4
. 6 | 4 | 6, 5+1, 4+2, 3+3 27 | 1 | 22+5
. 7 | 4 | 7, 6+1, 5+2, 4+3 28 | 1 | 22+6
. 8 | 5 | 8, 7+1, 6+2, 5+3, 4+4 29 | 1 | 22+7
. 9 | 5 | 9, 8+1, 7+2, 6+3, 5+4 30 | 1 | 22+8
. 10 | 5 | 9+1, 8+2, 7+3, 6+4, 5+5 31 | 1 | 22+9
. 11 | 5 | 11, 9+2, 8+3, 7+4, 6+5 32 | 0 | ./.
. 12 | 5 | 11+1, 9+3, 8+4, 7+5, 6+6 33 | 2 | 33, 22+11
. 13 | 4 | 11+2, 9+4, 8+5, 7+6 34 | 1 | 33+1
. 14 | 4 | 11+3, 9+5, 8+6, 7+7 35 | 1 | 33+2
. 15 | 3 | 11+4, 9+6, 8+7 36 | 1 | 33+3
. 16 | 3 | 11+5, 9+7, 8+8 37 | 1 | 33+4
. 17 | 2 | 11+6, 9+8 38 | 1 | 33+5
. 18 | 2 | 11+7, 9+9 39 | 1 | 33+6
. 19 | 1 | 11+8 40 | 1 | 33+7
. 20 | 1 | 11+9 41 | 1 | 33+8 .
PROG
(Haskell)
a260254 n = sum $ map (a136522 . (n -)) $
takeWhile (<= n `div` 2) a002113_list
CROSSREFS
KEYWORD
nonn,base,look
AUTHOR
Reinhard Zumkeller, Jul 21 2015
STATUS
approved