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.

A109617 Numbers k such that (10's complement factorial of k) - 1 is prime.

Original entry on oeis.org

2, 3, 4, 7, 77, 337, 397, 566, 615, 822, 1007, 1017, 1073, 1351, 1731, 2635, 6606, 8513, 10404
Offset: 1

Views

Author

Jason Earls, Aug 01 2005

Keywords

Examples

			3 is a term because (10-3)*(10-2)*(10-1) - 1 = 503 is prime.
77 is a term because (100-77)*..*(100-10)*(10-9)*..*(10-1) - 1 is prime.

Crossrefs

Cf. A109616, A110396.

Extensions

a(9)-a(17) from Jinyuan Wang, Aug 09 2025
a(18)-a(19) from Michael S. Branicky, Aug 13 2025

A109757 Numbers n such that (10's complement factorial of n) + 1 is semiprime.

Original entry on oeis.org

1, 3, 6, 14, 20, 21, 26, 34, 37, 39, 40, 47, 51, 54, 61, 62, 72, 74, 77, 82, 83, 86, 113, 115, 118, 127, 139, 179
Offset: 1

Views

Author

Jason Earls, Aug 12 2005

Keywords

Crossrefs

Cf. A110396, A109616.

Programs

Extensions

More terms from Sean A. Irvine, Jul 10 2011
Showing 1-2 of 2 results.

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

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