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

Author

Reinhard Zumkeller, Nov 05 2001

Keywords

• nonn

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

Crossrefs

See A097050 for another version.

Cf. A065382, A007491, A064384, A000217.

Cf. A000217.

Programs

Haskell

a065383 n = head $ dropWhile (< a000217 n) a000040_list
-- Reinhard Zumkeller, Aug 03 2012

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 *)

PARI

{ for (n=0, 1000, write("b065383.txt", n, " ", nextprime(n*(n + 1)/2)) ) } \\ Harry J. Smith, Oct 17 2009

Extensions

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