OFFSET
1,2
COMMENTS
All terms in this sequence are also practical numbers. All multiples c*prime(n) are also primitive practical numbers (A267124). - Frank M Jackson, Oct 16 2024
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000
EXAMPLE
For n = 4 we have prime(n) = prime(4) = 7. The least k such that k*prime(4) is practical is k = 4, to get 28. Therefore, a(4) = 4.
PROG
(PARI) a(n) = my(p = prime(n)); for(i = 1, oo, if(is_A005153(p * i), return(i))) \\ David A. Corneth, Dec 31 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
David A. Corneth, Dec 05 2018
STATUS
approved