cp's OEIS Frontend

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.

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A262173 Number of nonnegative integers < 10^n that are palindromes or the sum of 2 palindromes.

Original entry on oeis.org

1, 10, 92, 991, 8012, 90970, 733052, 8861377, 68729295, 875790193
Offset: 0

Views

Author

Chai Wah Wu, Sep 18 2015

Keywords

Crossrefs

A309325 Numbers that are the sum of two successive palindromes.

Original entry on oeis.org

1, 3, 5, 7, 9, 11, 13, 15, 17, 20, 33, 55, 77, 99, 121, 143, 165, 187, 200, 212, 232, 252, 272, 292, 312, 332, 352, 372, 393, 414, 434, 454, 474, 494, 514, 534, 554, 574, 595, 616, 636, 656, 676, 696, 716, 736, 756, 776, 797, 818, 838, 858, 878, 898, 918, 938, 958, 978
Offset: 1

Views

Author

Ilya Gutkovskiy, Jul 23 2019

Keywords

Crossrefs

Programs

  • Mathematica
    Total /@ Partition[Select[Range[0, 500], PalindromeQ], 2, 1]
  • Python
    from itertools import chain, count, islice
    def A309325_gen(): # generator of terms
        c = 0
        for a in chain.from_iterable(chain((int((s:=str(d))+s[-2::-1]) for d in range(10**l,10**(l+1))), (int((s:=str(d))+s[::-1]) for d in range(10**l,10**(l+1)))) for l in count(0)):
            yield c+(c:=a)
    A309325_list = list(islice(A309325_gen(),20)) # Chai Wah Wu, Jun 23 2022

Formula

a(n) = A002113(n) + A002113(n+1).
Previous Showing 11-12 of 12 results.