OFFSET
1,2
COMMENTS
Any subsequent terms are > 10^10. - Lucas A. Brown, Dec 24 2022
LINKS
Lucas A. Brown, Python program.
Eric Weisstein's World of Mathematics, Centered Square Number
EXAMPLE
a(3) = 25 because 25 has 3 centered square divisors {1, 5, 25} and this is the smallest such number.
PROG
(PARI) iscsq(n) = issquare(2*n-1); \\ A001844
a(n) = my(k=1); while (sumdiv(k, d, iscsq(d)) != n, k++); k; \\ Michel Marcus, Nov 21 2022
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Ilya Gutkovskiy, Nov 21 2022
EXTENSIONS
a(12)-a(15) from Michel Marcus, Nov 21 2022
a(16) from Martin Ehrenstein, Dec 02 2022
a(17)-a(24) from Jinyuan Wang, Dec 02 2022
STATUS
approved