OFFSET
0,2
COMMENTS
a(n) is the smallest nonnegative k such that A092573(k) = n.
a(11) <= 3672178237.
a(12) = 6916.
a(13) = 33124.
a(14) = 29059303.
a(15) = 124852.
a(16) = 1983163.
a(18) = 48412.
a(20) = 18384457.
a(21) = 6117748.
a(22) = 1623076.
a(24) = 214396.
a(27) = 629356.
a(28) = 900838393.
a(31) = 79530724.
a(32) = 85276009.
a(37) = 274299844.
a(42) = 116237212.
a(60) = 73537828.
a(67) = 585930436.
From Chai Wah Wu, Jun 29-30 2024: (Start)
a(30) = 2372188.
a(36) = 1500772.
a(40) = 11957764.
a(45) = 30838444.
a(48) = 7932652.
a(54) = 19510036.
a(72) = 55528564.
(End)
EXAMPLE
n | a(n)
-----+---------------------------
1 | 4 = 2^2.
2 | 91 = 7 * 13.
3 | 28 = 2^2 * 7.
4 | 196 = 2^2 * 7^2.
5 | 31213 = 7^4 * 13.
6 | 364 = 2^2 * 7 * 13.
7 | 9604 = 2^2 * 7^4.
8 | 53599 = 7 * 13 * 19 * 31.
9 | 2548 = 2^2 * 7^2 * 13.
10 | 470596 = 2^2 * 7^6.
PROG
(Python)
from itertools import count
from sympy.abc import x, y
from sympy.solvers.diophantine.diophantine import diop_quadratic
def A374158(n): return next(m for m in count(0) if sum(1 for d in diop_quadratic(x**2+3*y**2-m) if d[0]>0 and d[1]>0)==n) # Chai Wah Wu, Jun 29 2024
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, Jun 29 2024
STATUS
approved