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A152859 Tower of prime powers: a(n)=prime(n)^a(n-1), a(0)=0. 1
0, 1, 3, 125, 4337654948097993282537354757263188251697832994620405101744893017744569432720994168089672192211758909320807 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Originally called "Exprimorial numbers (exponential prime factorials)", the strict analog would be "exponential primorial". [Editor's Note]

LINKS

Table of n, a(n) for n=0..4.

J. Sondow, Exponential Factorial

Wikipedia, Factorial

FORMULA

a(n) = 0 if n = 0; a(n) = prime(n) ^ a(n - 1), n >= 1.

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.

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

CROSSREFS

Cf. A002110, A049384.

Cf. A140319 (alternate definition: start with a(0)=1). - Paolo P. Lava, Jul 31 2018

Sequence in context: A085531 A130614 A114877 * A241647 A157547 A160879

Adjacent sequences:  A152856 A152857 A152858 * A152860 A152861 A152862

KEYWORD

nonn

AUTHOR

ShaoJun Ying (dolphinysj(AT)gmail.com), Dec 14 2008

EXTENSIONS

Edited by M. F. Hasler, Nov 01 2009

STATUS

approved

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Last modified January 17 05:13 EST 2022. Contains 350378 sequences. (Running on oeis4.)