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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A117125 Positive integers that can be expressed as the difference between a factorial and a double factorial.

Original entry on oeis.org

0, 1, 3, 4, 5, 9, 15, 16, 21, 22, 23, 72, 105, 112, 117, 118, 119, 336, 615, 672, 705, 712, 717, 718, 719, 1200, 4095, 4656, 4935, 4992, 5025, 5032, 5037, 5038, 5039
Offset: 1

Views

Author

Paolo P. Lava and Giorgio Balzarotti, Apr 20 2006

Keywords

Examples

			117 = 5! - 3!!
4992 = 7! - 6!!

Crossrefs

Cf. A110903, A111300.

Formula

n! - m!! being n! > m!!

A275540 a(n) = n! + n!! - n - 1.

Original entry on oeis.org

1, 0, 1, 5, 27, 129, 761, 5137, 40695, 363815, 3632629, 39927183, 479047667, 6227155921, 87178936305, 1307676395009, 20922800209903, 355687462555407, 6402373891522541, 121645101063561055, 2432902011892531179
Offset: 0

Views

Author

Olivier Gérard, Aug 01 2016

Keywords

Crossrefs

Cf. A006882, A110903, A128882.

Programs

  • Mathematica
    Table[n! + n!! - n - 1, {n, 0, 20}] (* Bruno Berselli, Aug 11 2016 *)
Showing 1-2 of 2 results.

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

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