OFFSET
0,1
COMMENTS
The sequence starts with a string of primes for indices n = 0 to 6. a(n=7)=851 is composite, n=8 to 9 are prime, n=10 to 11 are composite etc. with an irregular pattern of primes/composites.
LINKS
FORMULA
a(n) = 11 + 30*A000217(n). - Michel Marcus, Jun 24 2013
MATHEMATICA
Table[15n(n+1)+11, {n, 0, 40}] (* or *) LinearRecurrence[{3, -3, 1}, {11, 41, 101}, 40] (* Harvey P. Dale, Mar 01 2016 *)
PROG
(PARI) a(n) = 11 + 30*n*(n+1)/2 \\ Michel Marcus, Jun 24 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Nate Eskey (nj.eskey09(AT)bchigh.edu), Nov 06 2007
EXTENSIONS
Better definition from R. J. Mathar, Nov 16 2007
STATUS
approved