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.

A175486 Composite numbers of form 8n+5 with all prime factors of form 8m+5.

Original entry on oeis.org

125, 325, 725, 845, 925, 1325, 1525, 1885, 2197, 2405, 2525, 2725, 3125, 3445, 3725, 3925, 3965, 4205, 4325, 4525, 4901, 4925, 5365, 5725, 6253, 6565, 6725, 6845, 6925, 7085, 7325, 7685, 7925, 8125, 8725, 8845, 8957, 9325, 9685, 9725, 9805, 9925, 10205
Offset: 1

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Author

Zak Seidov, May 27 2010

Keywords

Comments

There are no squares and no semiprimes in the sequence.

Examples

			125=5^3, 325=5^2*13, 725=5^2*29.
		

Crossrefs

Cf. A004770 Numbers of form 8n+5, A175461 Semiprimes of form 8n+5, A007521 Primes of form 8n+5.

Programs

  • Mathematica
    Do[nn=8n+5;If[ !PrimeQ[nn]&&{5}==Union[Mod[(fi=First/@FactorInteger[nn]),8]],Print[nn]],{n,2*10^3}]