OFFSET
1,1
COMMENTS
Essentially, i.e., except for a(1), identical to A007702. All terms are primitive abundant numbers (A091191) and thus, except for the first term, odd primitive abundant (A006038). The next term is too large to be displayed here, see A007707 (and formula) for many more terms, using a more compact encoding. - M. F. Hasler, Apr 30 2017
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..14
G. Thimm, Emails to N. J. A. Sloane, Sep. 1994
FORMULA
a(n) = Product_{k=n..A007707(n)} prime(k) = Product_{0 <= i < A108227(n)} prime(n+i). - M. F. Hasler, Apr 30 2017 and Jun 15 2017
MATHEMATICA
a[n_] := Module[{p = Prime[n]}, r = 1; prod = 1; While[r <= 2, r *= 1 + 1/p; prod *= p; p = NextPrime[p]]; prod]; Array[a, 5] (* Amiram Eldar, Jun 29 2019 *)
PROG
(PARI) a(n) = {p = prime(n); sig = p+1; prd = p; while (sig <= 2*prd, p = nextprime(p+1); sig *= p+1; prd *= p; ); return (prd); } \\ Michel Marcus, Mar 10 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Don Reble, Nov 10 2005
STATUS
approved