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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A347075 Primes of the form p^3 + p^2 + p + 2 where p is prime.

Original entry on oeis.org

41, 157, 401, 2381, 12721, 25261, 81401, 499361, 712981, 1455781, 2705081, 4357481, 7226501, 7684381, 7920401, 12061661, 12703861, 21330941, 22745561, 31955821, 49565921, 54583961, 59015581, 127517041, 237560441, 384769841, 455348741, 506897581, 570410861, 591294481, 866432341, 905167121
Offset: 1

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Author

J. M. Bergot and Robert Israel, Aug 15 2021

Keywords

Comments

Except for 157, all terms == 1 (mod 20).

Examples

			a(3) = 401 because 401 = 7^3 + 7^2 + 7 + 2 and 7 and 401 are prime.
		

Crossrefs

Cf. A164939.

Programs

  • Maple
    f:= proc(p) local q;
    if not isprime(p) then return NULL fi;
    q:= p^3+p^2+p+2;
    if isprime(q) then return q fi
    end proc:
    map(f, [seq(i,i=3..1000,2)]);

Formula

a(n) = A164939(n)^3 + A164939(n)^2 + A164939(n) + 2.
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