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A321340 a(1) = 1; thereafter a(n) = a(n-1) * prime(n-1)^a(n-1). 1
1, 2, 18, 68664550781250 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
The prime factorization of a(n) describes all previous terms in the sequence: a(n) = prime(1)^a(1) * prime(2)^a(2) * prime(3)^a(3) * ...* prime(n-1)^a(n-1).
An infinite and monotonically increasing sequence which grows very rapidly.
LINKS
EXAMPLE
68664550781250 = 2 * 3^2 * 5^18 = prime(1)^1 * prime(2)^2 * prime(3)^18.
MATHEMATICA
Nest[Append[#, #[[-1]] Prime[Length@ #]^#[[-1]] ] &, {1}, 3] (* Michael De Vlieger, Nov 05 2018 *)
PROG
(PARI) apply( ppp(n) = prod(i=1, n-1, prime(i)^ppp(i)), [1..4] )
CROSSREFS
Somewhat similar to A007097.
Cf. A321339.
Sequence in context: A293242 A321339 A086367 * A221229 A221602 A354207
KEYWORD
nonn
AUTHOR
Russell Y. Webb, Nov 05 2018
STATUS
approved

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Last modified April 14 00:20 EDT 2024. Contains 371652 sequences. (Running on oeis4.)