OFFSET
1,5
COMMENTS
Almost monotonically increasing sequence, only rarely a(n) <= a(n-1), contrary to case of n instead of prime(n) (A181786).
LINKS
Samuel Harkness, Table of n, a(n) for n = 1..1229
EXAMPLE
a(2)=1 because prime(2)=3 and 3^2 = 1^2 + 2^2 + 2^2,
a(4)=1 because prime(4)=7 and 7^2 = 2^2 + 3^2 + 6^2,
a(5)=2 because prime(5)=11 and 11^2 = 2^2 + 6^2 + 9^2 = 6^2 + 6^2 + 7^2.
MATHEMATICA
Table[Length[FindInstance[{Prime[n]^2==a^2+b^2+c^2, 0<a<=b<=c}, {a, b, c}, Integers, 100]], {n, 80}] (* Harvey P. Dale, Mar 06 2020 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Mar 02 2012
STATUS
approved