A065383 - OEIS

%I #25 Dec 11 2022 13:42:29

%S 2,2,3,7,11,17,23,29,37,47,59,67,79,97,107,127,137,157,173,191,211,

%T 233,257,277,307,331,353,379,409,439,467,499,541,563,599,631,673,709,

%U 743,787,821,863,907,947,991,1039,1087,1129,1181,1229,1277,1327,1381,1433

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

%C Besides 7, terms exclude the greater of the twin primes (A006512). - _Bill McEachen_, Dec 01 2022

%H Harry J. Smith, <a href="/A065383/b065383.txt">Table of n, a(n) for n = 0..1000</a>

%t 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 *)

%t NextPrime/@(Accumulate[Range[0,60]]-1) (* _Harvey P. Dale_, Jul 31 2012 *)

%o (PARI) { for (n=0, 1000, write("b065383.txt", n, " ", nextprime(n*(n + 1)/2)) ) } \\ _Harry J. Smith_, Oct 17 2009

%o (Haskell)

%o a065383 n = head $ dropWhile (< a000217 n) a000040_list

%o -- _Reinhard Zumkeller_, Aug 03 2012

%Y See A097050 for another version.

%Y Cf. A065382, A007491, A064384, A000217.

%Y Cf. A000217.

%K nonn

%O 0,1

%A _Reinhard Zumkeller_, Nov 05 2001

%E Edited by _N. J. A. Sloane_, Nov 21 2008