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.

A239523 Prime powers (A025475) such that the distances to the two nearest prime powers are primes.

Original entry on oeis.org

1, 25, 27, 32, 128, 512, 2048, 8192, 32768, 562949953421312
Offset: 1

Views

Author

Alex Ratushnyak, Mar 20 2014

Keywords

Comments

A subsequence of A239522.
a(4)...a(10) are powers of 2, a(10) = 2^49.

Crossrefs

Cf. A025475, A239520 - A239522.

A239522 Prime powers (A025475) such that the distance to the nearest prime power is a prime.

Original entry on oeis.org

1, 4, 16, 25, 27, 32, 81, 125, 128, 169, 243, 256, 512, 529, 2048, 7921, 8192, 32761, 32768, 130321, 131072, 134689, 524288, 2093809, 2097152, 8388608, 8392609, 134217728, 134258569, 536870912, 536987929, 8590138489, 140737625897521, 562949953421312, 562950076511761
Offset: 1

Views

Author

Alex Ratushnyak, Mar 20 2014

Keywords

Crossrefs

Cf. A025475, A239520 - A239523.

A239521 Prime powers (A025475) such that the distance to the nearest prime power is an oblong number (A002378).

Original entry on oeis.org

25, 27, 2209, 3481, 3721, 6859, 6889, 18769, 22201, 22801, 157609, 1079521, 1630729, 1635841, 2621161, 2627641, 2825761, 3179089, 5257849, 5276209, 7447441, 7458361, 17032129, 17048641, 34304449, 34351321, 40436881, 40462321, 75290329, 75359761, 137288089, 137334961
Offset: 1

Views

Author

Alex Ratushnyak, Mar 20 2014

Keywords

Crossrefs

Cf. A002378, A025475, A239520 - A239523.

Programs

  • PARI
    lista(nn) = {precp = 1; currp = 4; for (nextp=5, nn, if (is_A025475(nextp), if (currp - precp < nextp - currp, tt = currp - precp, tt = nextp - currp); if (!(tt % 2) && ispolygonal(tt/2, 3), print1(currp, ", ")); precp = currp; currp = nextp;););} \\ Michel Marcus, Apr 11 2014
Showing 1-3 of 3 results.

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