A161550 Largest prime <= n^2+n.

2, 5, 11, 19, 29, 41, 53, 71, 89, 109, 131, 151, 181, 199, 239, 271, 293, 337, 379, 419, 461, 503, 547, 599, 647, 701, 751, 811, 863, 929, 991, 1051, 1117, 1187, 1259, 1327, 1399, 1481, 1559, 1637, 1721, 1801, 1889, 1979, 2069, 2161, 2251, 2351, 2447, 2549, 2647

Offset

1,1

Links

Nathaniel Johnston, Table of n, a(n) for n = 1..10000

Maple

A161550 := proc(n) return prevprime(n*(n+1)+1): end: seq(A161550(n), n=1..51); # Nathaniel Johnston, May 01 2011

Mathematica

PrimePrev[n_]:=Module[{k}, k=n-1; While[ !PrimeQ[k], k-- ]; k]; lst={}; Do[a=n^2+n; p=PrimePrev[a]; AppendTo[lst, p], {n, 2, 5!}]; lst (* Vladimir Joseph Stephan Orlovsky, Jun 13 2009 *)
Join[{2}, Table[NextPrime[n^2+n, -1], {n, 2, 60}]] (* Harvey P. Dale, May 01 2011 *)

Prog

(PARI) a(n)=precprime(n^2+n) \\ Charles R Greathouse IV, Mar 27 2014

Crossrefs

Sequence in context: A152471 A088796 A190309 * A245207 A215762 A085626

Adjacent sequences: A161547 A161548 A161549 * A161551 A161552 A161553

Keyword

easy,nonn

Author

Daniel Tisdale, Jun 13 2009

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Jun 13 2009

Status

approved