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 A126868 a(n) = (n+1)!! mod n. 0
 0, 1, 2, 3, 3, 3, 6, 1, 6, 5, 1, 3, 8, 7, 0, 1, 13, 9, 1, 15, 0, 11, 1, 9, 0, 13, 0, 7, 17, 15, 1, 1, 0, 17, 0, 27, 6, 19, 0, 25, 9, 21, 1, 11, 0, 23, 46, 33, 0, 25, 0, 39, 30, 27, 0, 49, 0, 29, 58, 15, 50, 31, 0, 1, 0, 33, 1, 51, 0, 35, 1, 9, 27, 37, 0, 19, 0, 39, 78, 65, 0, 41, 82, 63, 0, 43 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS EXAMPLE n=3 (n+1)!! = 4!! = 8; (8 mod 3) = 2. n=4 (n+1)!! = 5!! = 15; (15 mod 4) = 3. MAPLE P:=proc(n) local i, j, k, w; for i from 1 by 1 to n do k:=i+1; w:=i-1; while w>0 do k:=k*w; w:=w-2; od; j:=(k mod i); print(j); od; end: P(100); PROG (PARI) df(n) = prod(i=0, (n-1)\2, n - 2*i ); a(n) = df(n+1) % n; \\ Michel Marcus, Aug 22 2016 CROSSREFS Cf. A006882, A000165, A001147, A119688. Sequence in context: A264870 A131048 A119688 * A134187 A078644 A133700 Adjacent sequences:  A126865 A126866 A126867 * A126869 A126870 A126871 KEYWORD easy,nonn AUTHOR Paolo P. Lava and Giorgio Balzarotti, Mar 16 2007 STATUS approved

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Last modified May 9 09:12 EDT 2021. Contains 343699 sequences. (Running on oeis4.)