A121359 Greatest prime factor of pyramidal number A000292(n).

2, 5, 5, 7, 7, 7, 5, 11, 11, 13, 13, 13, 7, 17, 17, 19, 19, 19, 11, 23, 23, 23, 13, 13, 13, 29, 29, 31, 31, 31, 17, 17, 17, 37, 37, 37, 19, 41, 41, 43, 43, 43, 23, 47, 47, 47, 7, 17, 17, 53, 53, 53, 11, 19, 29, 59, 59, 61, 61, 61, 31, 13, 13, 67, 67, 67, 23, 71, 71, 73, 73, 73, 37

Offset

2,1

Comments

a(n) <= n+2, with equality if n+2 is prime. - Robert Israel, Feb 16 2023

Links

Robert Israel, Table of n, a(n) for n = 2..10000

Formula

a(n) = A006530(A000292(n)).

Maple

f:= n -> max(numtheory:-factorset(n*(n+1)*(n+2)/6)):
map(f, [$2..100]); # Robert Israel, Feb 16 2023

Mathematica

FactorInteger[#][[-1, 1]]&/@Binomial[Range[2, 80]+2, 3] (* Harvey P. Dale, Jan 31 2013 *)

Crossrefs

Cf. A000292, A006530.

Sequence in context: A197695 A245083 A233565 * A082087 A263317 A256300

Adjacent sequences: A121356 A121357 A121358 * A121360 A121361 A121362

Keyword

nonn

Author

Zak Seidov, Sep 06 2006

Extensions

Offset corrected by Robert Israel, Feb 16 2023

Status

approved