OFFSET
0,1
COMMENTS
An infinite coprime sequence defined by recursion.
Every term is relatively prime to all others. - Michael Somos, Feb 01 2004
REFERENCES
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
T. D. Noe, Table of n, a(n) for n=0..19
S. Kalpazidou et al., Lüroth-type alternating series representations for real numbers, Acta Arithmetica, 55 (1990), 311-322.
Jeffrey Shallit, Rational numbers with non-terminating, non-periodic modified Engel-type expansions, Fib. Quart., 31 (1993), 37-40.
FORMULA
a(2n) = A001075(2^n).
MATHEMATICA
nxt[{n_, a_, b_}]:=If[OddQ[n], {n+1, b, 2a^2-1}, {n+1, b, 2b-1}]; Transpose[ NestList[ nxt, {1, 2, 3}, 15]][[2]] (* Harvey P. Dale, Jun 22 2015 *)
PROG
(PARI) a(n)=if(n<1, 2*(n==0), if(n%2, 2*a(n-1)-1, 2*a(n-2)^2-1))
CROSSREFS
KEYWORD
nonn,easy,nice
AUTHOR
STATUS
approved