OFFSET
1,3
COMMENTS
Row length of irregular triangle A343239.
FORMULA
EXAMPLE
a(19) = 4 because A343238(19) = 42 = 2*3*7 has 2^(1+1) = 4 solutions from the primes 3 and 7.
PROG
(PARI) isok(k) = issquare(Mod(-5, k)); \\ A343238
lista(nn) = my(list = List()); for (n=1, nn, if (issquare(Mod(-5, n)), listput(list, sum(i=0, n-1, Mod(i, n)^2 + 5 == 0)); ); ); Vec(list); \\ Michel Marcus, Sep 17 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, May 16 2021
STATUS
approved