OFFSET
1,1
LINKS
K. D. Bajpai, Table of n, a(n) for n = 1..5666
EXAMPLE
157 is in the sequence because (7^2 + 11^2 + 13^2 + 17^2)/4 = 157 which is prime.
1213 is in the sequence because (29^2 + 31^2 + 37^2 + 41^2)/4 = 1213 which is prime.
MAPLE
KD := proc() local a, b, d, e, f, g; a:=ithprime(n); b:=ithprime(n+1); d:=ithprime(n+2); e:=ithprime(n+3); g:=(a^2+b^2+d^2+e^2)/4; if g=floor(g) and isprime(g) then RETURN (g); fi; end: seq(KD(), n=1..500);
MATHEMATICA
Select[Table[Mean[Prime[Range[n, n + 3]]^2], {n, 250}], PrimeQ] (* Alonso del Arte, Dec 26 2013 *)
Select[Mean/@(Partition[Prime[Range[200]], 4, 1]^2), PrimeQ] (* Harvey P. Dale, Oct 08 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
K. D. Bajpai, Dec 25 2013
STATUS
approved