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.

A075654 Numbers n such that n + sum of prime factors of n = (n+1) + sum of prime factors of (n+1).

Original entry on oeis.org

3, 14, 152, 224, 285, 455, 902, 1518, 2013, 2079, 4823, 6655, 7104, 7584, 8493, 8532, 9416, 14344, 15687, 18569, 20115, 20163, 20490, 22351, 25543, 26123, 28250, 28564, 30744, 37305, 37406, 41261, 45844, 50609, 51992, 54137, 56563, 60651
Offset: 1

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Author

Joseph L. Pe, Oct 11 2002

Keywords

Examples

			14 + sum of prime factors of 14 = 14 + 2 + 7 = 23; 15 + sum of prime factors of 15 = 15 + 3 + 5 = 23; hence 14 belongs to the sequence.
		

Crossrefs

Programs

  • Mathematica
    s[n_] := n + Apply[Plus, Transpose[FactorInteger[n]][[1]]]; Select[Range[2, 10^5], s[ # ] == s[ # + 1] &]
    SequencePosition[Table[n+Total[FactorInteger[n][[All,1]]],{n,70000}],{x_,x_}][[All,1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 23 2017 *)