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A214634 a(1) = 7; a(n) is smallest prime of the form k*a(n-1) + 3, k>0. 1
7, 17, 37, 151, 607, 1217, 2437, 4877, 39019, 78041, 624331, 6243313, 174812767, 1398502139, 19579029949, 39158059901, 1957902995053, 15663223960427, 156632239604273, 3132644792085463, 181693397940956857, 726773591763827431, 7267735917638274313, 1148302274986847341457, 4593209099947389365831 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..390

EXAMPLE

a(2) = 17 = 2 * 7 + 3.

a(3) = 37 = 2 * 17 + 3.

a(4) = 151 = 4 * 37 + 3.

MAPLE

A214634 := proc(n)

    option remember;

    local k;

    if n =  1 then

        7;

    else

        for k from 1 do

            if isprime(k*procname(n-1)+3) then

                return k*procname(n-1)+3 ;

            end if;

        end do:

    end if;

end proc:

seq(A214634(n), n=1..20) ; # R. J. Mathar, Jul 23 2012

MATHEMATICA

spf[n_]:=Module[{k=1}, While[!PrimeQ[k*n+3], k++]; k*n+3]; NestList[spf, 7, 25] (* Harvey P. Dale, Aug 02 2017 *)

PROG

(PARI)  a=7; for(n=1, 200, b=a*n+3; if(isprime(b), a=b; print1(a, ", "); next(n=1)))

CROSSREFS

Cf. A061092, A059411, A214523, A214632, A214633

Sequence in context: A090147 A211476 A155007 * A172156 A273947 A140121

Adjacent sequences:  A214631 A214632 A214633 * A214635 A214636 A214637

KEYWORD

nonn

AUTHOR

Robin Garcia, Jul 23 2012

EXTENSIONS

More terms from Robert Israel, Nov 23 2016

STATUS

approved

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Last modified September 29 21:59 EDT 2020. Contains 337432 sequences. (Running on oeis4.)