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 1-3 of 3 results.

A083547 a(n) = sqrt(sqrt(phi(A083546(n)) * phi(1+A083546(n)))), the 4th root of product of totients of terms and 1+terms of A082788.

Original entry on oeis.org

1, 12, 24, 36, 36, 60, 60, 72, 80, 96, 120, 120, 120, 144, 144, 168, 180, 240, 264, 360, 360, 432, 480, 504, 480, 480, 720, 720, 720, 720, 840, 840, 864, 840, 840, 840, 840, 960, 900, 960, 960, 1080, 1260, 1224, 1320, 1320, 1440, 1440, 1320, 1440, 1440, 1728
Offset: 1

Views

Author

Labos Elemer, May 21 2003

Keywords

Links

Crossrefs

Cf. A000010, A082788, A083538, A083542, A083545, A083546.

Programs

  • Mathematica
    f[x_] := EulerPhi[x]; Do[s=Sqrt[Sqrt[f[n+1]*f[n]]]; If[IntegerQ[s], Print[s]], {n, 1, 1000000}]

Extensions

a(29)-a(52) from Amiram Eldar, Apr 09 2021

A082811 Smallest multiple of n beginning with 2.

Original entry on oeis.org

2, 2, 21, 20, 20, 24, 21, 24, 27, 20, 22, 24, 26, 28, 210, 208, 204, 216, 209, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 210, 217, 224, 231, 204, 210, 216, 222, 228, 234, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 200, 204, 208, 212, 216, 220
Offset: 1

Views

Author

Amarnath Murthy, Apr 19 2003

Keywords

Comments

a(n) is in {n, 2n, 3n, 4n, 5n, 6n, 7n, 11n, 12n, 13n, 14n}. [Charles R Greathouse IV, Mar 06 2011]

Links

Crossrefs

Cf. A082784, A054850, A082786, A082787, A082788, A082789, A082791.
Cf. A000030.

Programs

  • Haskell
    a082811 n = until ((== 2) . a000030) (+ n) n
-- Reinhard Zumkeller, Mar 27 2012
  • Mathematica
    f[n_] := Block[{m = n}, While[ First@ IntegerDigits@ m != 2, m += n]; m]; Array[f, 55] (* Robert G. Wilson v *)
  • PARI
    a(n)=forstep(k=n, 14*n, n, if(Vec(Str(k))[1]=="2", return(k))) \\ Charles R Greathouse IV, Mar 06 2011
  • Sage
    def A082811(n): return next(k for k in PositiveIntegers() if (n*k).digits()[-1] == 2) # D. S. McNeil, Mar 07 2011

A082791 Smallest k such that k*n begins with 2: a(n) = A082811(n)/n.

Original entry on oeis.org

2, 1, 7, 5, 4, 4, 3, 3, 3, 2, 2, 2, 2, 2, 14, 13, 12, 12, 11, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 7, 7, 7, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3
Offset: 1

Views

Author

Amarnath Murthy, Apr 19 2003

Keywords

Comments

a(n) is in {1, 2, 3, 4, 5, 6, 7, 11, 12, 13, 14}. [Charles R Greathouse IV, Mar 06 2011]

Links

Crossrefs

Cf. A082784, A054850, A082786, A082787, A082788, A082789, A082811.

Programs

Extensions

More terms from Zak Seidov, Mar 06 2011
Showing 1-3 of 3 results.

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

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