A140319 Exponential primorial: a(n)=prime(n)^a(n-1), a(0)=1, where prime(n)=A000040(n).

1, 2, 9, 1953125

Offset

0,2

Comments

The next term is too large to include.

Links

Table of n, a(n) for n=0..3.

Jonathan Sondow, Exponential Factorial, Eric Weisstein's World of Mathematics.

Formula

Sum_{n>=0} 1/a(n) = A167155. - Amiram Eldar, Nov 15 2020

Example

a(1) = prime(1)^a(0) = 2^1 = 2.
a(2) = 3^2 = 9.
a(3) = 5^9 = 1953125.
a(4) = 7^1953125 has 1650583 digits, starting with 12864794... and ending in ...31920807. [M. F. Hasler, Nov 03 2009]

Maple

P:=proc(n) local a, i; a:=2; print(a); for i from 2 by 1 to n do a:=ithprime(i)^a; print(a); od; end: P(5);

Prog

(PARI) A140319(n)=if(n, prime(n)^A140319(n-1), 1) \\ M. F. Hasler, Nov 03 2009

Crossrefs

Cf. A002110, A049384, A139802, A167155.

Cf. A152859 (alternate definition: start with a(0)=0), A167155. [M. F. Hasler, Nov 03 2009]

Sequence in context: A132859 A103562 A309861 * A120314 A050924 A181500

Adjacent sequences: A140316 A140317 A140318 * A140320 A140321 A140322

Keyword

easy,nonn

Author

Paolo P. Lava and Giorgio Balzarotti, May 26 2008

Extensions

Corrected offset/definition, and initial a(0)=1 from M. F. Hasler, Nov 03 2009

Status

approved