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A152859
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Tower of prime powers: a(n)=prime(n)^a(n-1), a(0)=0.
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1
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OFFSET
| 0,3
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COMMENTS
| Originally called "Exprimorial numbers (exponential prime factorials)", the strict analogue would be "exponential primorial". [Editor's Note]
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LINKS
| Wikipedia, Factorial
J. Sondow, "Exponential Factorial."
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FORMULA
| a(n) = 0 if n = 0; a(n) = prime(n) ^ a(n - 1), n >= 1.
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EXAMPLE
| a(4) = 7 ^ a(3) = 7 ^ 125
a(5) = 11 ^ a(4) has approximately 4.5 * 10^105 digits, starting with 335856... and ending in ...815171
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PROG
| (C) unsigned long Exprimorial(unsigned int n) {
if (n == 0) return 0;
return pow(prime(n), Exprimorial(n - 1));
}
(PARI) vector(4, i, t=if(i==1, 1, prime(i)^t)) /* indices are shifted by 1 */ [M. F. Hasler, Nov 01 2009]
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CROSSREFS
| Cf. A002110, A049384
Sequence in context: * A085531 A130614 A114877 A157547 A160879 A157562
Adjacent sequences: A152856 A152857 A152858 * A152860 A152861 A152862
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KEYWORD
| nonn
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AUTHOR
| ShaoJun Ying (dolphinysj(AT)gmail.com), Dec 14 2008
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EXTENSIONS
| Edited by M. F. Hasler (www.univ-ag.fr/~mhasler), Nov 01 2009
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