OFFSET
1,2
COMMENTS
Companion sequence to A318527, as it is shown there that all terms in A318527 are congruent to 1 mod 360.
Also numbers k such that -3 is a quadratic residue modulo (360*k + 1)*(360*k + 2)*(360*k + 3)*(360*k + 4)/2.
The number of terms <= 1000, 10000 and 100000 are 156, 1100 and 8056, respectively. There are also 22 pairs of consecutive numbers <= 1000, 99 pairs <= 10000 and 540 pairs <= 100000.
LINKS
Altug Alkan, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = (A318527(n) - 1)/360.
EXAMPLE
2 is a term since 93^2 == -3 (mod 721), 137^2 == -3 (mod 722), 210^2 == -3 (mod 723) and 97^2 == -3 (mod 724).
PROG
(PARI) isA057128(n) = issquare(Mod(-3, n));
isA318911(n) = isA057128(360*n+1) && isA057128(360*n+2) && isA057128(360*n+3) && isA057128(360*n+4);
CROSSREFS
KEYWORD
nonn
AUTHOR
Jianing Song, Sep 05 2018
STATUS
approved