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.

A213353 A subset of numbers n such that n^4 is a Sierpinski number.

Original entry on oeis.org

44745755, 1812338107, 9266824499, 12308871853, 13657352875, 22767480811, 22930161667, 24068927659, 25549554505, 25770503549, 57939582163, 90219135299, 90329609821, 96949951147, 103126759951
Offset: 1

Views

Author

Arkadiusz Wesolowski, Jun 09 2012

Keywords

Comments

A sequence constructed from Izotov's trick.
If n belongs to this sequence and n does not end in 5, then n^4 has the covering set {3, 5, 17, 97, 241, 257, 673}.

Links

Crossrefs

Subset of A233469. Cf. A076336.

Programs

  • Mathematica
    (* even if nn is increased, no additional terms are generated *) nn = 14; lst = {}; n = 44745755; p = 2^12; m = 3*(p^4 - 1)/(p - 1); Do[a = n + (-1)^c*m; n = a/GCD[a, p]; AppendTo[lst, Abs@n], {c, 0, nn}]; Union@lst

A270895 Sierpiński numbers that are squares.

Original entry on oeis.org

18213931681, 5044241991721, 6093734165401, 6278567569849, 17919144076201, 52536446729209, 56470430531761, 72659547739249, 107737943736721, 123343213788001, 136925780937841, 170306127919321, 211292941174561, 296693149397089, 321058916825689
Offset: 1

Views

Author

Arkadiusz Wesolowski, Mar 25 2016

Keywords

Comments

This sequence contains infinitely many numbers that end in 5. See also A233469.

Links

Crossrefs

Cf. A076336, A233469, A270896.

Formula

A000290 INTERSECT A076336.
a(n) = A270896(n)^2.

A270896 Values of n for which n^2 is a Sierpiński number.

Original entry on oeis.org

134959, 2245939, 2468549, 2505707, 4233101, 7248203, 7514681, 8524057, 10379689, 11105999, 11701529, 13050139, 14535919, 17224783, 17918117, 20887471, 22609447, 23352049, 26616221, 29156453, 29583953, 29913997, 31273301, 32046613, 35672821, 35882309
Offset: 1

Views

Author

Arkadiusz Wesolowski, Mar 25 2016

Keywords

Links

Crossrefs

Cf. A076336, A233469, A270895.

Formula

a(n) = sqrt(A270895(n)).
Showing 1-3 of 3 results.

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

Content is available under The OEIS End-User License Agreement.