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.

Showing 1-2 of 2 results.

A224532 Largest number k such that phi(k) = A007374(n).

Original entry on oeis.org

2, 6, 12, 30, 42, 120, 126, 150, 90, 210, 660, 1242, 7938, 2760, 1014, 270, 1470, 810, 3318, 630, 2370, 4830, 7590, 1386, 11220, 1680, 1260, 5082, 13890, 1050, 3570, 33750, 1890, 26082, 14058, 2310, 2730, 5670, 5250, 70140, 12690, 14280, 12474, 3990, 11850
Offset: 2

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Author

T. D. Noe, Apr 11 2013

Keywords

Comments

That is, the largest number k such that phi(k) = x, with x being the least number having n solutions. - T. D. Noe, Apr 14 2013

Crossrefs

Cf. A224531.

Programs

  • Mathematica
    Needs["CNT`"]; nn = 50; t = Table[0, {nn}]; n = 0; left = nn - 1; While[left > 0, n++; cnt = Length[PhiInverse[n]]; If[cnt <= nn && t[[cnt]] == 0, t[[cnt]] = n; left--]]; Join[{0}, Table[PhiInverse[n][[-1]], {n, Rest[t]}]]

A066420 Least m such that card(invphi(phi(m)))=n.

Original entry on oeis.org

1, 3, 5, 15, 13, 51, 37, 41, 35, 65, 187, 397, 2269, 1059, 313, 73, 337, 247, 937, 185, 689, 1139, 2057, 403, 2827, 485, 323, 1321, 3697, 241, 769, 9001, 433, 7129, 4201, 527, 577, 1297, 1201, 15937, 3313, 3281, 3379, 949, 3121, 7519, 3889, 779, 1763
Offset: 2

Views

Author

Vladeta Jovovic, Dec 25 2001

Keywords

Crossrefs

Formula

a(n) = A049283(A007374(n)). - Max Alekseyev, Apr 12 2005

Extensions

More terms from Max Alekseyev, Apr 12 2005
Showing 1-2 of 2 results.