OFFSET
1,1
COMMENTS
5 divides (4^m+1) for odd m, so every term in this sequence is a multiple of 5 (A008587).
Every non-solvable number (A056866) is divisible by 12 or 20. All non-solvable numbers not divisible by 12 (A008594) are divisible by a member of this sequence. In particular, every primitive non-solvable number (A257146) not divisible by 12 is in this sequence.
All terms are divisible by 320 and have at least 4 distinct prime factors. - Jianing Song, Apr 04 2022
LINKS
Danny Rorabaugh, Table of n, a(n) for n = 1..100
MATHEMATICA
Table[4^p (4^p+1)(2^p-1), {p, Prime[Range[2, 20]]}] (* Harvey P. Dale, Jul 17 2024 *)
PROG
(Sage) [4^nth_prime(n)*(4^nth_prime(n)+1)*(2^nth_prime(n)-1) for n in range(2, 12)]
(PARI) a(n)=my(p=prime(n+1)); 4^p*(4^p+1)*(2^p-1) \\ Charles R Greathouse IV, Apr 21 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Danny Rorabaugh, Apr 21 2015
STATUS
approved