A083558 p(p^2-p+1) as p runs through the primes.

6, 21, 105, 301, 1221, 2041, 4641, 6517, 11661, 23577, 28861, 49321, 67281, 77701, 101661, 146121, 201957, 223321, 296341, 352941, 383761, 486877, 564981, 697137, 903361, 1020201, 1082221, 1213701, 1283257, 1430241, 2032381, 2231061, 2552721, 2666437

Offset: 1

Author

N. J. A. Sloane, Jun 15 2003

Keywords

• nonn

Comments

Warning: not all quizzes permit the use of the OEIS!

Discard (from the list of integers) numbers that have exactly 1 factor of prime(n) in their prime factorization. Of those remaining, the proportion that have exactly 2 factors of prime(n) is (prime(n)-1)/a(n). - Peter Munn, Nov 27 2020

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000040, A119959.

Programs

Magma

[p*(p^2-p+1): p in PrimesUpTo(150)]; // Vincenzo Librandi, Jan 10 2017

Mathematica

Table[p(p^2-p+1),{p,Prime[Range[40]]}] (* Harvey P. Dale, Jan 09 2017 *)

Formula

a(n) = A000040(n) * A119959(n). - Peter Munn, Nov 29 2020