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A225371
a(n) = number of squares in M(n,2), the ring of n X n matrices over GF(2).
6
1, 2, 10, 260, 31096, 13711952, 28275659056, 224402782202048, 7293836994286696576, 952002419516769475035392, 497678654312172407869125822976, 1044660329769242614113093804053562368, 8745525723307044762290950664928498588583936
OFFSET
0,2
COMMENTS
a(0)-a(4) computed by W. Edwin Clark, May 07 2013.
A226321 is a similar sequence which counts the real {0,1} matrices which are the square of a {0,1} matrix. - Giovanni Resta, Jun 03 2013
PROG
(PARI) a(n)=#vecsort(lift(vector(2^n^2, k, matrix(n, n, i, j, bittest(k, (i-1)*n+j-1))^2*Mod(1, 2))), , 8) \\ Charles R Greathouse IV, May 07 2013
(PARI) ZM(k)=matrix(n, n, i, j, bittest(k, (i-1)*n+j-1))*Mod(1, 2)
MZ(M)=my(n=matsize(M)[1]); sum(i=1, n, sum(j=1, n, M[i, j]<<((i-1)*n+j-1)))
a(n)=#vecsort(vector(2^n^2, i, MZ(lift(ZM(i, n)^2))), , 8) \\ Charles R Greathouse IV, May 07 2013
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
N. J. A. Sloane, May 07 2013
EXTENSIONS
a(5)-a(6) from Giovanni Resta, May 08 2013
a(7)-a(30) from Victor S. Miller, May 24 2013
STATUS
approved