OFFSET
17,1
COMMENTS
a(n+1)-a(n)+14 is either 15 or a prime > 17. For a generalization, see the second Shevelev link. - Edited by Robert Israel, Aug 21 2017
LINKS
Robert Israel, Table of n, a(n) for n = 17..10000
E. S. Rowland, A natural prime-generating recurrence, Journal of Integer Sequences, Vol. 11 (2008), Article 08.2.8.
V. Shevelev, A new generator of primes based on the Rowland idea, arXiv:0910.4676 [math.NT], 2009.
V. Shevelev, Generalizations of the Rowland theorem, arXiv:0911.3491 [math.NT], 2009-2010.
MAPLE
A[17]:= 37:
q:= convert(select(isprime, [$2..17]), `*`);
for n from 18 to 100 do
if igcd(n, A[n-1]) > 1 and igcd(n, q) = 1 then A[n]:= 3*n-14
else A[n]:= A[n-1]+1 fi
od:
seq(A[i], i=17..100); # Robert Israel, Aug 21 2017
MATHEMATICA
nxt[{n_, a_}]:={n+1, If[GCD[n+1, a]>1&&FactorInteger[n+1][[1, 1]]>17, 3(n+1)-14, a+1]}; NestList[nxt, {17, 37}, 60][[All, 2]] (* Harvey P. Dale, Aug 15 2017 *)
CROSSREFS
KEYWORD
nonn,changed
AUTHOR
Vladimir Shevelev, Nov 19 2009
EXTENSIONS
Corrected by Harvey P. Dale, Aug 15 2017
STATUS
approved