1/4 the number of n X n arrays of squares of integers with every 2X2 subblock summing to 21.

A159222

1/4 the number of n X n arrays of squares of integers with every 2X2 subblock summing to 21.

Terms

    a(0) =7a(1) =20a(2) =45a(3) =95a(4) =193a(5) =389a(6) =777a(7) =1553a(8) =3097a(9) =6185a(10) =12345a(11) =24665a(12) =49273a(13) =98489a(14) =196857a(15) =393593a(16) =786937a(17) =1573625a(18) =3146745a(19) =6292985a(20) =12584953a(21) =25168889a(22) =50335737a(23) =100669433a(24) =201334777a(25) =402665465

External references