A085819 a(n) = Product_{k<=n} A085818(k).

1, 2, 6, 12, 60, 420, 4620, 9240, 27720, 360360, 6126120, 116396280, 2677114440, 77636318760, 2406725881560, 4813451763120, 178097715235440, 7302006324653040, 313986271960080720, 14757354782123793840

Offset: 1

Author

Reinhard Zumkeller, Jul 04 2003

Keywords

• nonn

Comments

n divides a(n), see A085818.

Crossrefs

Cf. A000040, A000142, A002110, A085818.

Programs

PARI

f(n) = 1 + sum(k=2, n, isprimepower(k) && !isprime(k));  \\ A085501
b(n) = {if (n==1, return (1)); my(p); if (isprimepower(n, &p) && !isprime(n), p, prime(n-f(n))); } \\ A085818
a(n) = prod(k=1, n, b(k)); \\ Michel Marcus, Jul 13 2021