A065383 a(n) = smallest prime >= n*(n + 1)/2.

2, 2, 3, 7, 11, 17, 23, 29, 37, 47, 59, 67, 79, 97, 107, 127, 137, 157, 173, 191, 211, 233, 257, 277, 307, 331, 353, 379, 409, 439, 467, 499, 541, 563, 599, 631, 673, 709, 743, 787, 821, 863, 907, 947, 991, 1039, 1087, 1129, 1181, 1229, 1277, 1327, 1381, 1433

Offset

0,1

Comments

Besides 7, terms exclude the greater of the twin primes (A006512). - Bill McEachen, Dec 01 2022

Links

Harry J. Smith, Table of n, a(n) for n = 0..1000

Mathematica

PrimeNext[n_]:=Module[{k=n}, While[ !PrimeQ[k], k++ ]; k]; f[n_]:=n*(n+1)/2; lst={}; Do[AppendTo[lst, PrimeNext[f[n]]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Feb 26 2010 *)
NextPrime/@(Accumulate[Range[0, 60]]-1) (* Harvey P. Dale, Jul 31 2012 *)

Prog

(PARI) { for (n=0, 1000, write("b065383.txt", n, " ", nextprime(n*(n + 1)/2)) ) } \\ Harry J. Smith, Oct 17 2009
(Haskell)
a065383 n = head $ dropWhile (< a000217 n) a000040_list
-- Reinhard Zumkeller, Aug 03 2012

Crossrefs

See A097050 for another version.

Cf. A065382, A007491, A064384, A000217.

Cf. A000217.

Sequence in context: A208494 A036060 A227300 * A087384 A179283 A234850

Adjacent sequences: A065380 A065381 A065382 * A065384 A065385 A065386

Keyword

nonn

Author

Reinhard Zumkeller, Nov 05 2001

Extensions

Edited by N. J. A. Sloane, Nov 21 2008

Status

approved