OFFSET
1,1
COMMENTS
a(60) > 10^10 and a(68) > 10^13. - Martin Ehrenstein, Nov 09 2022
LINKS
Todor Szimeonov, Square of prime numbers
EXAMPLE
For n=7, prime(7) = 17 and starting there 2 primes 17 + 19 = 36 which is square, so that a(7)=2.
MAPLE
f:= proc(n) local p, s, k;
p:= ithprime(n); s:= p;
for k from 2 do
p:= nextprime(p);
s:= s+p;
if issqr(s) then return k fi
od
end proc:
map(f, [$1..36]); # Robert Israel, Nov 08 2022
MATHEMATICA
a[n_] := Module[{p = s = Prime[n], k = 1}, While[! IntegerQ[Sqrt[s]], p = NextPrime[p]; s += p; k++]; k]; Array[a, 36] (* Amiram Eldar, Nov 08 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Todor Szimeonov, Nov 01 2022
EXTENSIONS
a(25)-a(36) from Robert Israel, Nov 08 2022
a(37)-a(59) from Martin Ehrenstein, Nov 09 2022
STATUS
approved