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 A102049 Indices of primes which are denominators of convergents to e. 2
 2, 4, 20, 2073, 688812, 23493068282804, 51287550456151700 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The prime denominators of convergents to e form A094008 (so A000040(a(n)) = A094008(n)). Their positions in A007677 (denominators of convergents to e) form A094007, so a(n) = A000720(A007677(A094007(n))). a(6)-a(7) computed using Kim Walisch's primecount program. - Giovanni Resta, Jun 03 2019 LINKS E. B. Burger, Diophantine Olympics and World Champions: Polynomials and Primes Down Under, Amer. Math. Monthly, 107 (Nov. 2000), 822-829. J. Sondow, A geometric proof that e is irrational and a new measure of its irrationality, Amer. Math. Monthly 113 (2006) 637-641 (article), 114 (2007) 659 (addendum). J. Sondow, A geometric proof that e is irrational and a new measure of its irrationality, arXiv:0704.1282 [math.HO], 2007-2010. J. Sondow and K. Schalm, Which partial sums of the Taylor series for e are convergents to e? (and a link to the primes 2, 5, 13, 37, 463), II, Gems in Experimental Mathematics (T. Amdeberhan, L. A. Medina, and V. H. Moll, eds.), Contemporary Mathematics, vol. 517, Amer. Math. Soc., Providence, RI, 2010; arXiv:0709.0671 [math.NT], 2007-2009. Eric Weisstein's World of Mathematics, e. FORMULA a(n) = A000720(A094008(n)). EXAMPLE a(1) = 2 because the first convergent to e with prime denominator is 8/3 and the index of 3 is 2, i.e., 3 is the 2nd prime. CROSSREFS Cf. A000040, A000720, A007677, A094007, A094008. Sequence in context: A087314 A326972 A099179 * A058522 A292534 A122736 Adjacent sequences:  A102046 A102047 A102048 * A102050 A102051 A102052 KEYWORD nonn,more AUTHOR Jonathan Sondow, Dec 27 2004 EXTENSIONS a(6)-a(7) from Giovanni Resta, Jun 03 2019 STATUS approved

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Last modified November 19 16:06 EST 2019. Contains 329320 sequences. (Running on oeis4.)