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.

A066251 Inverse permutation to A066250.

Original entry on oeis.org

1, 3, 2, 5, 4, 7, 6, 8, 10, 9, 12, 11, 16, 13, 18, 14, 22, 15, 28, 17, 30, 19, 36, 20, 40, 21, 42, 23, 46, 24, 52, 25, 58, 26, 60, 27, 66, 29, 70, 31, 72, 32, 78, 33, 82, 34, 88, 35, 96, 37, 100, 38, 102, 39, 106, 41, 108, 43, 112, 44, 126, 45, 130, 47, 136, 48, 138, 49, 148
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 09 2001

Keywords

Comments

Permutation of natural numbers.

Links

Crossrefs

Cf. A066250, A000040, A002808, A066248, A066255.

Formula

a(n) = (if n is odd then A000040((n+1)/2) else A002808(n/2)) - 1.

A066254 a(n) = A066250(A066250(n)).

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 16, 13, 15, 14, 24, 18, 17, 30, 34, 20, 19, 21, 42, 46, 23, 22, 52, 26, 25, 27, 60, 29, 66, 28, 70, 31, 76, 32, 80, 36, 33, 35, 88, 38, 92, 37, 98, 39, 41, 40, 106, 110, 43, 116, 45, 44, 122, 48, 126, 47, 132, 136, 140, 50, 49, 146, 51
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 09 2001

Keywords

Comments

Permutation of natural numbers.

Links

A066248 a(n) = if n+1 is prime then A049084(n+1)*2 else A066246(n+1)*2 - 1.

Original entry on oeis.org

2, 4, 1, 6, 3, 8, 5, 7, 9, 10, 11, 12, 13, 15, 17, 14, 19, 16, 21, 23, 25, 18, 27, 29, 31, 33, 35, 20, 37, 22, 39, 41, 43, 45, 47, 24, 49, 51, 53, 26, 55, 28, 57, 59, 61, 30, 63, 65, 67, 69, 71, 32, 73, 75, 77, 79, 81, 34, 83, 36, 85, 87, 89, 91, 93, 38, 95, 97, 99, 40, 101, 42
Offset: 1

Views

Author

Reinhard Zumkeller, Dec 09 2001

Keywords

Comments

Permutation of natural numbers; inverse: A066249.

Links

Crossrefs

Cf. A066249, A049084, A066246, A026238, A066247, A066250, A066252.

Programs

  • Mathematica
    a[n_] := If[PrimeQ[n+1], 2 * PrimePi[n+1], 2 * (n - PrimePi[n+1]) - 1]; Array[a, 100] (* Amiram Eldar, Mar 19 2025 *)

Formula

a(n) = A026238(n+1)*2 - A066247(n+1).
Showing 1-3 of 3 results.

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

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