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A165422 a(1) = 1, a(2) = 4, a(n) = product of the previous terms for n >= 3. 1
1, 4, 4, 16, 256, 65536, 4294967296, 18446744073709551616, 340282366920938463463374607431768211456, 115792089237316195423570985008687907853269984665640564039457584007913129639936 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..13

FORMULA

a(1) = 1, a(2) = 4, a(n) = Product_{i=1..n-1} a(i), n >= 3.

a(1) = 1, a(2) = 4, a(n) = A000302(2^(n-3)) = A001146(n-2) = 2^(2^(n-2)), n >= 3.

a(1) = 1, a(2) = 4, a(3) = 4, a(n) = (a(n-1))^2, n >= 4.

MATHEMATICA

a[1]:= 1; a[2]:= 4; a[n_] := Product[a[j], {j, 1, n-1}]; Table[a[n], {n, 1, 12}] (* G. C. Greubel, Oct 19 2018 *)

Join[{1, 4}, NestList[#^2&, 4, 10]] (* Harvey P. Dale, Aug 26 2019 *)

PROG

(PARI) {a(n) = if(n==1, 1, if(n==2, 4, prod(j=1, n-1, a(j))))};

for(n=1, 10, print1(a(n), ", ")) \\ G. C. Greubel, Oct 19 2018

CROSSREFS

Sequence in context: A263389 A019062 A019013 * A051460 A191972 A101407

Adjacent sequences:  A165419 A165420 A165421 * A165423 A165424 A165425

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Sep 17 2009

STATUS

approved

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Last modified February 25 21:00 EST 2020. Contains 332258 sequences. (Running on oeis4.)