A159048 Primes of the form m*(m+1)/2 + 4.
5, 7, 19, 59, 109, 157, 257, 439, 599, 907, 1039, 1229, 1279, 1489, 1657, 3407, 3659, 4099, 5569, 6907, 7507, 7879, 8389, 9049, 10589, 11329, 11939, 14369, 16657, 17209, 17959, 18149, 18919, 19507, 20507, 22159, 26339, 30139, 31379, 34457, 36319
Offset: 1
Keywords
Examples
7=3+4, 19=15+4, 59=55+4, 109=105+4, 157=153+4, 257=253+4, ...
Links
- G. C. Greubel, Table of n, a(n) for n = 1..1000
Programs
-
Mathematica
Select[Accumulate[Range[500]]+4,PrimeQ] (* Harvey P. Dale, Apr 23 2011 *)
-
PARI
for(n=1, 500, if(isprime(k=n*(n+1)/2 + 4), print1(k, ", "))) \\ G. C. Greubel, Jul 03 2017
Extensions
Edited by N. J. A. Sloane, Apr 06 2009