A239111 - OEIS

%I #23 Feb 14 2016 10:36:40

%S 2,12,5,70,13860,169,408,15994428,93222358,29,107578520350,6625109,

%T 2378,24580185800219268,143263821649299118,7645370045,15994428,

%U 259717522849,37774750930342781945186508,220167382952941249990598278,21300003689580,3166815962,50305164660422142002238655969020

%N Smallest Pell number (see A000129) divisible by n-th prime.

%H Alois P. Heinz, <a href="/A239111/b239111.txt">Table of n, a(n) for n = 1..350</a>

%H J. L. Schiffman, <a href="http://archives.math.utk.edu/ICTCM/i/24/C027.html">Exploring the Fibonacci sequence of order two with CAS technology</a>, Paper C027, Electronic Proceedings of the Twenty-fourth Annual International Conference on Technology in Collegiate Mathematics, Orlando, Florida, March 22-25, 2012.

%p p:= proc(n) p(n):=`if`(n<2, n, 2*p(n-1)+p(n-2)) end:

%p a:= proc(n) local k, t; t:= ithprime(n);

%p       for k while irem(p(k), t)>0 do od; p(k)

%p     end:

%p seq(a(n), n=1..23);  # _Alois P. Heinz_, Mar 28 2014

%t p[n_] := p[n] = If[n<2, n, 2*p[n-1] + p[n-2]]; a[n_] := With[{t = Prime[n]} , For[k=1, Mod[p[k], t] > 0, k++]; p[k]]; Table[a[n], {n, 1, 23}] (* _Jean-François Alcover_, Feb 14 2016, after _Alois P. Heinz_ *)

%Y Cf. A120947.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Mar 27 2014