This site is supported by donations to The OEIS Foundation. Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A002715 An infinite coprime sequence defined by recursion. (Formerly M2683 N1073) 5
 3, 7, 23, 47, 1103, 2207, 2435423, 4870847, 11862575248703, 23725150497407, 281441383062305809756861823, 562882766124611619513723647, 158418504200047111075388369241884118003210485743490303 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Every term is relatively prime to all others. REFERENCES N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..21 A. W. F. Edwards, Infinite coprime sequences, Math. Gaz., 48 (1964), 416-422. A. W. F. Edwards, Infinite coprime sequences, Math. Gaz., 48 (1964), 416-422. [Annotated scanned copy] R. Mestrovic, Euclid's theorem on the infinitude of primes: a historical survey of its proofs (300 BC--2012) and another new proof, arXiv preprint arXiv:1202.3670 [math.HO], 2012-2018. FORMULA a(2n+1) = 2*a(2n)+1, a(2n) = (a(2n-1)^2-3)/2, with a(0)=3. MATHEMATICA a[n_?OddQ] := a[n] = 2*a[n-1] + 1; a[n_?EvenQ] := a[n] = (a[n-1]^2 - 3)/2; a = 3; Table[a[n], {n, 0, 12}] (* Jean-François Alcover, Jan 25 2013 *) PROG (PARI) a(n)=if(n<1, 3*(n==0), if(n%2, 2*a(n-1)+1, (a(n-1)^2-3)/2)) CROSSREFS Cf. A001685, A003686, A064526. Sequence in context: A054270 A058000 A246497 * A112052 A205491 A203253 Adjacent sequences:  A002712 A002713 A002714 * A002716 A002717 A002718 KEYWORD nonn AUTHOR EXTENSIONS More terms from Jeffrey Shallit. Edited by Michael Somos, Feb 01 2004 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 24 14:08 EDT 2019. Contains 326280 sequences. (Running on oeis4.)