A385380 Partial products of the sequence nonprime powers of primes (A025475).

1, 4, 32, 288, 4608, 115200, 3110400, 99532800, 4877107200, 312134860800, 25282923724800, 3059233770700800, 382404221337600000, 48947740331212800000, 8272168115974963200000, 2010136852181916057600000, 514595034158570510745600000, 148717964871826877605478400000

Offset: 1

Author

Amiram Eldar, Jun 27 2025

Keywords

• nonn
• easy

Comments

Indices of records in A385379.

a(n) is the least index k such that A385379(k) = n-1.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..217
• Index entries for sequences related to powerful numbers.

Crossrefs

Cf. A024923, A025475, A385379.

Subsequence of A001694 and A025487 (i.e., of A181800).

Programs

Mathematica

FoldList[Times, 1, Select[Range[250], !PrimeQ[#] && PrimePowerQ[#] &]] (* Amiram Eldar, Jun 27 2025 *)

PARI

list(lim) = {my(p = 1); print1(p, ", "); for(k = 2, lim, if(isprimepower(k) > 1, p *= k; print1(p, ", ")));}

Formula

a(n) = Product_{k=1..n} A025475(k).