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.

A087993 Numbers k for which the quotient q(k)=(k+rev(k))/abs(k-rev(k)) is an integer.

Original entry on oeis.org

45, 54, 495, 594, 4356, 4545, 4995, 5454, 5895, 5985, 5994, 6534, 10890, 19602, 20691, 29403, 30492, 39204, 40293, 43956, 45045, 49005, 49995, 50094, 54054, 59994, 65934, 68607, 70686, 77319, 91377, 109890, 197802, 208791, 296703, 307692
Offset: 1

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Author

Labos Elemer, Oct 08 2003

Keywords

Examples

			n = 45, rev(n) = 54, q = 99/9 = 9 integer;
n = 934065, rev(n) = 560434, q = 1494504/373626 = 4, integer.
		

Crossrefs

Cf. A087994 (the quotients), A118959.

Programs

  • Mathematica
    rev[n_] := FromDigits@ Reverse@ IntegerDigits@ n; Select[Range[10^5], # != (r = rev[#]) && Mod[# + r, # - r] == 0 &] (* Giovanni Resta, May 14 2017 *)