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 A024957 a(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=2 and a(2)=a(3)=1. 0
 2, 1, 1, 2, 4, 9, 20, 44, 97, 230, 540, 1257, 2920, 7168, 17393, 41806, 100408, 250098, 618124, 1517008, 3716627, 9375710, 23479016, 58419236, 145210076, 368786352, 931600246, 2341625080, 5877503872, 15027036202, 38225273720, 96794415372 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS CROSSREFS Sequence in context: A333450 A210112 A024735 * A153914 A151893 A326566 Adjacent sequences:  A024954 A024955 A024956 * A024958 A024959 A024960 KEYWORD nonn AUTHOR EXTENSIONS Offset corrected and title improved by Sean A. Irvine, Jul 30 2019 STATUS approved

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Last modified November 26 12:37 EST 2020. Contains 338639 sequences. (Running on oeis4.)