login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A007686 Prime(n)*...*a(n) is the least product of consecutive primes which is non-deficient. 4
3, 13, 31, 73, 149, 233, 367, 521, 733, 991, 1249, 1579, 1949, 2341, 2791, 3343, 3881, 4481, 5147, 5849, 6619, 7499, 8387, 9341, 10321, 11411, 12517, 13709, 15013, 16363, 17881, 19381, 20873, 22369, 24007, 25763, 27611, 29399, 31357 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Differs from A007708 only for n=1. - Michel Marcus, Mar 10 2013
LINKS
H. W. Gould, A class of binomial sums and a series transform, Utilitas Math., 45 (1994), 71-83. (Annotated scanned copy) [Annotation on p. 81 references this A-number, but the sequence with that annotation is apparently unrelated to this entry and is not present in the OEIS to date. - Andrey Zabolotskiy, Jul 16 2022]
MATHEMATICA
a[n_] := Module[{p = Prime[n]}, r = 1 + 1/p; While[r < 2, p = NextPrime[p]; r *= 1 + 1/p]; p]; Array[a, 39] (* 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 (p); } \\ Michel Marcus, Mar 10 2013
CROSSREFS
Sequence in context: A106090 A067980 A164569 * A147030 A146259 A146174
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Don Reble, Nov 10 2005
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 13 14:26 EDT 2024. Contains 371642 sequences. (Running on oeis4.)