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 A211173 (2n)!^n (modulo 2n+1). 1
 0, 2, 1, 6, 0, 10, 1, 0, 1, 18, 0, 22, 0, 0, 1, 30, 0, 0, 1, 0, 1, 42, 0, 46, 0, 0, 1, 0, 0, 58, 1, 0, 0, 66, 0, 70, 1, 0, 0, 78, 0, 82, 0, 0, 1, 0, 0, 0, 1, 0, 1, 102, 0, 106, 1, 0, 1, 0, 0, 0, 0, 0, 0, 126, 0, 130, 0, 0, 1, 138, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS a(n)= 0, 1 or 2n. In fact, a(n) = 0 iff n belongs to A047845, a(n) = 1 iff n belongs to A104636 and a(n) = 2n iff n belongs to A104635. LINKS Charles R Greathouse IV, Table of n, a(n) for n = 0..10000 Larry Riddle, Sophie Germain and Fermat's Last Theorem, Agnes Scott College, Math. Dept. Jul, 1999. FORMULA a(n) = (2n)!^n (modulo 2n+1). MATHEMATICA f[n_] := Mod[((2 n)!)^n, 2 n + 1]; Array[f, 70] Table[PowerMod[(2n)!, n, 2n+1], {n, 0, 70}] (* Harvey P. Dale, Nov 02 2019 *) PROG (PARI) a(n)=if(isprime(2*n+1), if(n%2, 2*n, 1), 0) \\ Charles R Greathouse IV, Feb 07 2013 CROSSREFS Cf. A047845, A104635, A104636. Sequence in context: A370901 A198812 A155183 * A163553 A078503 A288052 Adjacent sequences: A211170 A211171 A211172 * A211174 A211175 A211176 KEYWORD nonn,easy AUTHOR Larry Riddle (LRiddle(AT)AgnesScott.edu) and Robert G. Wilson v, Jan 31 2013 STATUS approved

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Last modified April 17 04:44 EDT 2024. Contains 371756 sequences. (Running on oeis4.)