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 A185457 a(n) = abs( Im((2+i)^(2^n)) ). 2
 1, 4, 24, 336, 354144, 116749235904, 22940770664883067253376, 182503181432559739767250904458105698387204864 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS The next term is too large to be displayed here. Old name was: Leg of primitive Pythagorean triangle generated by repeated application of the basic formula y(n) = 2*x(n-1)*y(n-1), x(1)=2, y(1)=1. LINKS Alois P. Heinz, Table of n, a(n) for n = 0..11 FORMULA a(n) = abs( Im((2+i)^(2^n)) ). EXAMPLE y(2)=24 since x(1)=3, y(1)=4 are the two legs of Pythagorean triangle obtained by p=2, q=1; second iteration p=3, q=4 gives 2*3*4=24. MAPLE a:= n-> abs(Im((2+I)^(2^n))): seq(a(n), n=0..8); # Alois P. Heinz, Apr 25 2013 MATHEMATICA Table[Abs[Im[(2 + I)^(2^n)]], {n, 0, 10}] (* G. C. Greubel, Jul 07 2017 *) PROG (PARI) a(n) = abs(imag((2+I)^(2^n))); \\ Joerg Arndt, Apr 25 2013 (Python) from sympy import im, I def a(n): return abs(im((2 + I)**(2**n))) print([a(n) for n in range(11)]) # Indranil Ghosh, Jul 08 2017 CROSSREFS Cf. A176594, A120905. Cf. A099456 ( imaginary part of (2+i)^n ). Sequence in context: A206239 A361054 A196687 * A024250 A167140 A010572 Adjacent sequences: A185454 A185455 A185456 * A185458 A185459 A185460 KEYWORD nonn,less AUTHOR Carmine Suriano, Feb 04 2011 EXTENSIONS Better name from Joerg Arndt, Apr 25 2013 STATUS approved

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Last modified September 30 18:08 EDT 2023. Contains 365792 sequences. (Running on oeis4.)