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.

A140197 A137576((k-1)/2) for composite numbers k from A141229.

Original entry on oeis.org

55, 301, 3631, 6085, 19495, 70645, 147853, 438205, 605695, 669781, 888823, 1694695, 3060301, 3640783, 6692791, 7998895, 9857245, 12912535, 15443365, 17109895, 17690941, 22819693, 28048231, 34936663, 58178245, 75203725, 95263573, 124984543, 127160245, 155267965
Offset: 1

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Author

Vladimir Shevelev, Jun 15 2008

Keywords

Crossrefs

Programs

  • Mathematica
    r[n_] := EulerPhi[n]/MultiplicativeOrder[2, n]; d[n_] := DivisorSum[n, r[#] &]; f[n_] := (m = MultiplicativeOrder[2, n])*d[n] - m + 1; f /@ Select[Range[10^5], CompositeQ[#] && Total@(r /@ Divisors[#]) - 1 == 3 &] (* Amiram Eldar, Sep 12 2019 *)

Extensions

More terms from Amiram Eldar, Sep 12 2019