STATUS
reviewed
approved
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Revision History for A323501
(Bold, blue-underlined text is an addition; faded, red-underlined text is aShowing entries 1-10 | older changes
STATUS
proposed
reviewed
STATUS
editing
proposed
FORMULA
From Andrew Howroyd, Sep 09 2019: (Start)
a(n) = (n/2)! * (n + 1)/2 for n mod 4 = 0;
a(n) = ((n-1)/2)! for n mod 4 = 1;
a(n) = (n/2-1)! * (n^2 + n + 2)/4 for n mod 4 = 2;
a(n) = ((n-3)/2)! * (n + 1)*(n^3 + n^2 - 6*n + 6)/16 for n mod 4 = 3.
(End)
PROG
(PARI) a(n)=(n\4*2)!*if(n%4<2, if(n%2==0, (n + 1)/2, 1), if(n%2==0, (n^2 + n + 2)/4, (n + 1)*(n^3 + n^2 - 6*n + 6)/16)); \\ Andrew Howroyd, Sep 09 2019
CROSSREFS
Cf. A323500 (white black bishop graph).
LINKS
Andrew Howroyd, <a href="/A323501/b323501.txt">Table of n, a(n) for n = 2..50</a>
DATA
2, 6, 5, 2, 22, 356, 108, 24, 672, 25056, 4680, 720, 38160, 2531520, 342720, 40320, 3467520, 358444800, 38102400, 3628800, 460857600, 68388364800, 5987520000, 479001600, 84304281600, 16979648716800, 1264085222400, 87178291200, 20312541849600
OFFSET
1,2,1
PROG
(PARI) \\ See A289170 for DomSetCount, Bishop.
a(n)={Vec(DomSetCount(Bishop(n, 1), x + O(x^((n+3)\2))))[1]} \\ Andrew Howroyd, Sep 08 2019
KEYWORD
nonn,more
nonn
EXTENSIONS
Offset corrected and terms a(11) and beyond from Andrew Howroyd, Sep 08 2019
STATUS
approved
editing
STATUS
proposed
approved
STATUS
editing
proposed