|
%I #9 Mar 31 2012 13:22:09
%S 1,2,5,8,16,18,20,28,25,30,40,46,41,53,56,73,62,66,81,93,85,84,89,97,
%T 101,127,121,122,119,128,150,141,144,152,150,143,174,203,197,195,196,
%U 194,213,213,218,223,230,235,249,258,256,244,264,262
%N a(n) is the number of odd primes p < prime(n)^2 such that prime(n)# + p is prime with prime(n)# primorial of prime(n).
%C a(n) is not so far from prime(n).
%H Pierre CAMI, <a href="/A186413/b186413.txt">Table of n, a(n) for n = 1..176</a>
%e prime(1)#=2 2+3=5 5>2^2 so a(1)=1
%e prime(2)#=6 6+5=11,6+7=13 11>3*3 so a(2)=2
%o SCRIPT
%o DIM nn,1
%o DIM kk
%o DIM cc
%o DIM dd
%o DIMS tt
%o DIMS ss
%o OPENFILEOUT myout,res
%o LABEL loopn
%o SET nn,nn+1
%o SET kk,nn
%o SET cc,0
%o SET dd,0
%o LABEL loopk
%o SET kk,kk+1
%o IF p(kk)>p(nn)^2 THEN GOTO a
%o SETS tt,%d,%d,%d\,;nn;p(nn);-p(kk)
%o PRP p(nn)#-p(kk),tt
%o IF ISPRIME THEN SET cc,cc+1
%o IF ISPRP THEN SET cc,cc+1
%o SETS tt,%d,%d,%d\,;nn;p(nn);p(kk)
%o PRP p(nn)#+p(kk),tt
%o IF ISPRIME THEN SET dd,dd+1
%o IF ISPRP THEN SET dd,dd+1
%o GOTO loopk
%o LABEL a
%o SETS ss,%d,%d,%d\,;nn;cc;dd
%o WRITE myout,ss
%o GOTO loopn
%Y Cf. A185398.
%K nonn
%O 1,2
%A _Pierre CAMI_, Feb 21 2011
|
