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 A260658 Numerators of a BBP-like formula for 4*Pi/sqrt(27). 1
 5, -7, 23, -1, 41, -25, 59, -17, 77, -43, 95, -13, 113, -61, 131, -35, 149, -79, 167, -11, 185, -97, 203, -53, 221, -115, 239, -31, 257, -133, 275, -71, 293, -151, 311, -5, 329, -169, 347, -89, 365, -187, 383, -49, 401, -205, 419, -107, 437, -223, 455, -29, 473 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS 4*Pi/sqrt(27) = Sum_{n >= 0} (-1/8)^n*(2/(3*n+1)+1/(3*n+2)). LINKS David H. Bailey, A Compendium of BBP-Type Formulas for Mathematical Constants. David Brink, Nilakantha's accelerated series for pi, Acta Arith. 171 (2015), 293-308. FORMULA a(n) = numerator((-1/8)^n*(2/(3*n+1)+1/(3*n+2))). PROG (PARI) a(n) = numerator((-1/8)^n*(2/(3*n+1) + 1/(3*n+2))); \\ Michel Marcus, Nov 15 2015 (MAGMA) [Numerator((-1/8)^n*(2/(3*n+1)+1/(3*n+2))): n in [0..60]]; // Vincenzo Librandi, Nov 20 2015 CROSSREFS Cf. A073010, A260659. Sequence in context: A248086 A076409 A294154 * A028281 A240102 A105890 Adjacent sequences:  A260655 A260656 A260657 * A260659 A260660 A260661 KEYWORD sign,frac AUTHOR David Brink, Nov 13 2015 EXTENSIONS More terms from Michel Marcus, Nov 15 2015 STATUS approved

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Last modified April 12 18:58 EDT 2021. Contains 342932 sequences. (Running on oeis4.)