A046116 - OEIS

A046116

Numbers k such that no Paley-type Hadamard matrix of order k exists.

92, 116, 156, 172, 184, 188, 232, 236, 260, 268, 292, 324, 356, 372, 376, 404, 412, 428, 436, 452, 472, 476, 508, 520, 532, 536, 584, 596, 604, 612, 652, 668, 712, 716, 732, 756, 764, 772, 808, 836, 852, 856, 872, 876, 892, 904, 932, 940, 944, 952, 956

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..51.

Joerg Arndt, Matters Computational (The Fxtbook).

Eric Weisstein's World of Mathematics, Hadamard Matrix.

Eric Weisstein's World of Mathematics, Paley Class.

FORMULA

Divisible by 4 but not of form 2^a*(q+1), q = odd prime power.

PROG

(PARI) isp(k) = for (i=0, valuation(k, 2), if (isprimepower(k/2^i-1, &p) && (p%2), return(1)); ); return(0);