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A004076 Number of hooked Skolem sequences of order n. 1

%I #27 Oct 24 2023 19:24:00

%S 0,1,2,0,0,38,124,0,0,12808,72648,0,0,21878816,168870048,0,0,

%T 113071735648,1105816948032,0,0,1395701792232832

%N Number of hooked Skolem sequences of order n.

%D CRC Handbook of Combinatorial Designs, 1996, p. 460.

%H Jeppe Winther Larsen, <a href="https://pdfs.semanticscholar.org/6377/9c279f8e27f5ed46ff6fe5c0624eebe5de7e.pdf">Counting the Skolem sequences using inclusion-exclusion</a>, 2009

%e For n = 3, there are 2 solutions: 1 1 2 3 2 0 3 and 3 1 1 3 2 0 2.

%K nonn,more

%O 1,3

%A _N. J. A. Sloane_

%E a(15)-a(18) from Jeppe Winther Larsen (jwl(AT)itu.dk), Oct 12 2009

%E a(4)-a(18) confirmed, a(3) corrected by _Fausto A. C. Cariboni_, Apr 11 2017

%E a(19)-a(22) from _Fausto A. C. Cariboni_, Apr 25 2017

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Last modified July 23 04:10 EDT 2024. Contains 374544 sequences. (Running on oeis4.)