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 A067652 a(n) = H_n(2,3) = H_(n-1)(2,4) where H_n is the n-th hyperoperator. 2
 4, 5, 6, 8, 16, 65536 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Originally named "2 plus 3, twice 3, 2 to the power of 3, etc." For hyperoperator definitions and links, see A054871. For nonnegative n, H_(n)(2,3) = H_(n-1)(2,H_(n-1)(2,2)) = H_(n-1)(2,4) or in the clearer square bracket notation: 2[n]3 = 2[n-1]2[n-1]2 = 2[n-1]4. - Natan Arie Consigli, Dec 07 2015 LINKS EXAMPLE H_0(2,3) = 3+1 = 4; H_1(2,3) = 2+3 = 5; H_2(2,3) = 2*3 = 6; H_3(2,3) = 2^3 = 2*2*2 = 2*4 = H_2(2,4) = 8; H_4(2,3) = 2^^3 = 2^2^2 =  2^4 = H_3(2,4) = 16; H_5(2,3) = 2^^^3 = 2^^2^^2 = 2^^4 = H_4(2,4) = 2^2^2^2 = 2^16 = 65536; H_6(2,3) = 2^^^^3 = 2^^^2^^^2 = 2^^^4 = H_5(2,4) = 2^^2^^2^^2 = 2^^65536 = 2^2^...^2^2, with 65536 2's. PROG (Haskell) f a 0 = 2 + a / f 0 1 = 0 / f 0 n = 1 / f a n = f (f (a-1) n) (n-1) CROSSREFS Cf. A054871. Sequence in context: A105829 A143903 A006756 * A080805 A104626 A242955 Adjacent sequences:  A067649 A067650 A067651 * A067653 A067654 A067655 KEYWORD nonn,bref AUTHOR Ashley Yakeley (ashley(AT)yakeley.org), Feb 03 2002 EXTENSIONS Hyperoperator notation, new initial term, and examples by Danny Rorabaugh, Oct 14 2015 Sequence merged with H_(n)(2,4) by Natan Arie Consigli, Dec 07 2015 STATUS approved

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Last modified January 18 09:26 EST 2022. Contains 350454 sequences. (Running on oeis4.)