A261924 - OEIS

A261924

Numbers that are the sum of two palindromes of the same length.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 22, 33, 44, 55, 66, 77, 88, 99, 110, 121, 132, 143, 154, 165, 176, 187, 198, 202, 212, 222, 232, 242, 252, 262, 272, 282, 292, 302, 303, 312, 313, 322, 323, 332, 333, 342, 343, 352, 353, 362, 363, 372, 373, 382, 383, 393

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OFFSET

1,3

COMMENTS

Theorem: For a fixed value of d, adding two palindromes of length d in all possible ways produces 19 distinct sums if d=1, and 17*19^floor((d-1)/2) distinct sums if d>1. (The number of palindromes with d digits is 10 if d = 1, otherwise 9*10^floor((d-1)/2).) - N. J. A. Sloane, Dec 06 2015

LINKS

N. J. A. Sloane, Table of n, a(n) for n = 1..12956

CROSSREFS

Cf. A002113, A261921, A261925, etc.

Sequence in context: A246086 A194417 A246093 * A255421 A255407 A269171

Adjacent sequences: A261921 A261922 A261923 * A261925 A261926 A261927

KEYWORD

nonn,base

AUTHOR

David Applegate and N. J. A. Sloane, Sep 17 2015

EXTENSIONS

Modified to include the zero palindrome. - N. J. A. Sloane, Dec 06 2015

STATUS

approved