%I #17 Feb 25 2020 22:38:37
%S 0,2,7,23,119,839,9239,120119,2042039,38798759,892371479,25878772919,
%T 802241960519,29682952539239,1217001054108839,52331045326680119,
%U 2459559130353965639,130356633908760178919,7691041400616850556279,469153525437627883933079,31433286204321068223516379
%N a(n) is the smallest q such that the number of nonnegative k <= q, possessing the property that k + k*q - q is a square, is equal to 2^n.
%F a(n) = A102476(n) - 1. - _Jinyuan Wang_, Feb 25 2020
%e a(0) = 0 because 2^0 = 1 solution is 0 (where k=0).
%e a(1) = 2 because 2^1 = 2 solutions are 1 (1) and 4 (2).
%e a(2) = 7 because 2^2 = 4 solutions are 1 (1), 9 (2), 25(4), 49 (7).
%e a(3) = 23 because 2^3 = 8 solutions are 1 (1), 25 (2), 49 (3), 121 (60, 169 (8), 289 (13), 361 (16), 529 (23).
%e a(4) = 119 because 2^4 = 16 solutions are 1 (1), 121 (2), 361 (4), 841 (8), 961 (9), 1681 (15), 2401 (21), 3481 (30), 3721 (32), 5041 (43), 6241 (53), 7921 (67), 8281 (70), 10201 (86), 11881 (100), 14161 (119).
%o (PARI) a(n) = {my(q=0); while (sum(k=0, q, issquare(k + k*q - q)) != 2^n, q++); q;} \\ _Michel Marcus_, Feb 25 2020
%Y Cf. A000290, A060594, A102476, A332761.
%K nonn
%O 0,2
%A _Juri-Stepan Gerasimov_, Feb 24 2020
%E a(7) from _Michel Marcus_, Feb 25 2020
%E More terms from _Jinyuan Wang_, Feb 25 2020