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.

A228575 Pseudoprimes n to base 2 such that n-4, n-2 and n+2 are primes.

Original entry on oeis.org

645, 656601, 6212361, 18958567881, 287468425245, 626160901281, 1395494019921, 1925525109201, 1960708164801, 1962378065901, 1977370759365, 2788325761551, 3032013857181, 6877227801081, 22298617759881, 30242009317521, 39454593651201, 42401101442001
Offset: 1

Views

Author

Shyam Sunder Gupta, Oct 27 2013

Keywords

Comments

All numbers in this sequence end in either 5 or 1.

Examples

			645 is a pseudoprime (base 2) and 641, 643 and 647 are primes.

Links

Crossrefs

Cf. A001567, A057942, A230488, A230489.

A230559 Pseudoprimes n to base 2 such that n-2, n+2 and n+4 are primes.

Original entry on oeis.org

634038307449, 4846359321105, 11927878640385, 20835183400305, 34166605315305, 54096163177785, 63154533545265, 88365393281985, 189080281720065, 850943773070385, 917252751841665, 1278728202166185, 1602254869802049, 3742704749436465, 6082185264252945
Offset: 1

Views

Author

Shyam Sunder Gupta, Oct 27 2013

Keywords

Comments

All numbers in this sequence end in either 5 or 9.

Examples

			634038307449 is a pseudoprime (base 2) and 634038307447, 634038307451 and 634038307453 are primes.

Links

Crossrefs

Cf. A001567, A057942, A230488, A230489, A228575.

A228455 Pseudoprimes n to base 2 such that n-2, n+2, n-4 and n+4 are primes.

Original entry on oeis.org

280743771536011785, 666787209284980785, 1386744766793550165, 6558237049521329745, 11646802313400102465
Offset: 1

Views

Author

Shyam Sunder Gupta, Oct 27 2013

Keywords

Comments

All numbers in this sequence end in 5 because n-4 , n-2 is a twin prime pair and so also is n+2 and n+4.
For all n, a(n) - 4 is in A230668(n). Somewhat surprisingly, all terms of A230668 known so far are of that form. - M. F. Hasler, Dec 08 2016

Examples

			280743771536011785 is a pseudoprime (base 2) and 280743771536011781, 280743771536011783, 280743771536011787 and 280743771536011789 are primes.

Crossrefs

Cf. A001567, A057942, A230488, A230489.
Showing 1-3 of 3 results.

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

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