

A329279


Number of distinct tilings of a 2n X 2n square with 1 x n polyominoes.


1



1, 9, 11, 19, 22, 33, 37, 51, 56, 73, 79, 99, 106, 129, 137, 163, 172, 201, 211, 243, 254, 289, 301, 339, 352, 393, 407, 451, 466, 513, 529, 579, 596, 649, 667, 723, 742, 801, 821, 883, 904, 969, 991, 1059, 1082, 1153, 1177, 1251, 1276, 1353, 1379, 1459, 1486, 1569, 1597, 1683, 1712, 1801, 1831
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OFFSET

1,2


COMMENTS

The positions of n X n subsquares greatly restricts which permutations are possible, simplifying finding solutions. a(n+1)  a(n) = A014682 (n+2), where A014682 is the Collatz function, except a(2)a(1) = 8 and A014682(4) = 5.


LINKS

Table of n, a(n) for n=1..59.
Jeff Bowermaster, Illustration of a(1)..a(3)
Jeff Bowermaster, Illustration of a(4) and a(5)
Jeff Bowermaster, Illustration of a(6)
Jeff Bowermaster, Illustration of a(7)
Jeff Bowermaster, Illustration of a(8)


FORMULA

For even n, a(n) = (n^2+4n)/2+3; for odd n, a(n) = (n^2+3n)/2+2 ; a(1) = 1.


PROG

(Pari) a(n) = if(n==1, 1, if(n%2, (n^2+3*n)/2+2, (n^2+4*n)/2+3))


CROSSREFS

Cf. A014682, A060312, A058331 (bisection).
Sequence in context: A263722 A299971 A090771 * A284295 A284294 A195572
Adjacent sequences: A329276 A329277 A329278 * A329280 A329281 A329282


KEYWORD

nonn


AUTHOR

Jeff Bowermaster, Nov 11 2019


STATUS

approved



