

A136687


Number of palindromes in the range [0,n] inclusive.


4



1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 16, 16, 16
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OFFSET

0,2


COMMENTS

Partial sums of A136522. [Typo fixed by Colin Barker, Apr 26 2015]


LINKS

N. J. A. Sloane, Table of n, a(n) for n = 0..20202


FORMULA

a(n) = inv_A002113(A261423(n)), where inv_A002113 is the inverse of A002113, i.e., it yields the index of a palindrome.  M. F. Hasler, Sep 10 2018


MATHEMATICA

palQ[n_]:=Module[{idn=IntegerDigits[n]}, idn==Reverse[idn]]; Accumulate[ Table[ If[palQ[n], 1, 0], {n, 0, 80}]] (* Harvey P. Dale, May 11 2014 *)


PROG

(PARI) A136687(n)=inv_A002113(A261423(n)) \\ M. F. Hasler, Sep 09 2018


CROSSREFS

Cf. A002113, A136522, A137180, A261423.
Sequence in context: A051503 A179622 A285757 * A086706 A100470 A071604
Adjacent sequences: A136684 A136685 A136686 * A136688 A136689 A136690


KEYWORD

nonn,base


AUTHOR

N. J. A. Sloane, Apr 21 2008


STATUS

approved



