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 A121206 a(n) = (2n)! mod n(2n+1). 0
 2, 4, 6, 0, 10, 12, 0, 16, 18, 0, 22, 0, 0, 28, 30, 0, 0, 36, 0, 40, 42, 0, 46, 0, 0, 52, 0, 0, 58, 60, 0, 0, 66, 0, 70, 72, 0, 0, 78, 0, 82, 0, 0, 88, 0, 0, 0, 96, 0, 100, 102, 0, 106, 108, 0, 112, 0, 0, 0, 0, 0, 0, 126, 0, 130, 0, 0, 136, 138, 0, 0, 0, 0, 148, 150, 0, 0, 156, 0, 0, 162 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If the zeros are removed and a 3 is inserted at the front, the first 3000 terms (or more) of the condensed sequence coincide with A039915. - R. J. Mathar, Mar 02 2007 LINKS FORMULA a(n) = A000142(2n) mod A000217(2n). EXAMPLE a(4) = 0 because 8*7*6*5*4*3*2*1 / 8+7+6+5+4+3+2+1 divides evenly (0 remainder). MATHEMATICA Table[Mod[(2n)!, n*(2n + 1)], {n, 85}] (* Ray Chandler *) CROSSREFS Cf. A005097 gives indices of nonzero terms; A047845 gives indices of zero terms. Cf. A039915, A006093. Sequence in context: A131806 A004518 A013670 * A062004 A300268 A009285 Adjacent sequences:  A121203 A121204 A121205 * A121207 A121208 A121209 KEYWORD nonn AUTHOR Ben Paul Thurston, Aug 20 2006 EXTENSIONS Edited, corrected and extended by R. J. Mathar and Ray Chandler, Aug 23 2006 STATUS approved

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Last modified October 20 22:44 EDT 2019. Contains 328291 sequences. (Running on oeis4.)