A060048 a(1) = 1 and for n>1 a(n) = Max { q prime | q# < prime(n)# / q# } where prime(i) = A000040(i) and p(i)# = A002110(i), primorial.

1, 2, 2, 3, 5, 5, 7, 11, 11, 13, 13, 17, 19, 19, 23, 23, 29, 31, 31, 37, 37, 41, 43, 43, 47, 47, 53, 53, 59, 61, 61, 67, 67, 71, 71, 73, 79, 79, 83, 83, 89, 97, 97, 101, 101, 103, 103, 107, 109, 109, 113, 113, 127, 127, 131, 131, 137, 139, 139, 149, 149, 151, 151, 157

Offset

1,2

Links

Table of n, a(n) for n=1..64.

Example

prime(10) = 29: 2*3*5*7*11*13 < 17*19*23*29 and as 2*3*5*7*11*13*17 > 19*23*29 we have a(10) = 13.

Prog

(PARI) primo(n) = factorback(primes(n)); \\ A002110
a(n) = {if (n==1, 1, my(iq=2, P= primo(n)); while (sqr(primo(iq))<P, iq++); prime(iq-1); ); } \\ Michel Marcus, Mar 04 2022

Crossrefs

Cf. A000040, A002110.

Sequence in context: A239482 A280470 A011971 * A110699 A035537 A285407

Adjacent sequences: A060045 A060046 A060047 * A060049 A060050 A060051

Keyword

nonn

Author

Reinhard Zumkeller, Oct 06 2001

Status

approved