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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A292021 Lucas-Carmichael numbers that are congruent to 1 (mod 4).

Original entry on oeis.org

20705, 80189, 120581, 1162349, 7274249, 8734109, 10260809, 14658349, 49412285, 90393029, 105818129, 110066669, 125532329, 256074029, 362868329, 366648281, 395032609, 434886605, 503733257, 558705449, 563601257, 574342145, 640057109, 939989609, 962529749
Offset: 1

Views

Author

Amiram Eldar, Sep 07 2017

Keywords

Comments

Most Lucas-Carmichael numbers are congruent to 3 (mod 4). Of the 9967 numbers less than 10^12 only 198 are congruent to 1 (mod 4).
Analogous to A185321 - Carmichael numbers that are congruent to 3 (mod 4).

Links

Crossrefs

Intersection of A006972 and A016813.
Cf. A110885, A185321.

Programs

  • Mathematica
    a=Select[Range[2, 10^6],!PrimeQ[#] && Union[Transpose[FactorInteger[#]][[2]]] == {1} && Union[Mod[# + 1, Transpose[FactorInteger[#]][[1]] + 1]]=={0} &] ;Select[a,Mod[#,4]==1 &] (* after Richard Pinch and Jeffrey Shallit at A006972 *)
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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