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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A232721 Numbers not representable as the sum of two coprime nonprime numbers.

Original entry on oeis.org

1, 3, 4, 6, 8, 12, 14, 18, 20, 24, 30, 32, 38, 42, 48, 54, 60, 72, 80, 84, 90, 108, 110, 132, 138, 140, 150, 180
Offset: 1

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Author

Irina Gerasimova, Nov 28 2013

Keywords

Comments

Numbers n such that A185279(n) = 0. 1 and 3 together with A141096.

Crossrefs

Cf. A062303, A018252, A141095, A141098.

Programs

  • Mathematica
    t = Table[Length[Select[Range[n/2], ! PrimeQ[#] && ! PrimeQ[n - #] && GCD[#, n - #] == 1 &]], {n, 2000}]; Flatten[Position[t, 0]] (* T. D. Noe, Dec 05 2013 *)
Showing 1-1 of 1 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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