The full stretch of composite numbers must begin and end with an even number as the prime before the stretch and the prime after the stretch must each be odd. So the stretch must have an odd number of composite members, if bounded by primes. (other than the zero composites between 2 and 3).
That of course makes a stretch of exactly 2000 impossible. The 2000 must be a subset of a larger stretch.
10 n=716632572105294061650160539001722
20 nn=fnNxprime(n):print nn
30 n=8072248000022287004415958958
40 nn=fnNxprime(n):print nn
80 end
90 '
10000 fnOddfact(N)
10010 local K=0,P
10030 while N@2=0
10040 N=N\2
10050 K=K+1
10060 wend
10070 P=pack(N,K)
10080 return(P)
10090 '
10100 fnPrime(N)
10110 local I,X,J,Y,Q,K,T,Ans
10120 if N@2=0 then Ans=0:goto *EndPrime
10125 O=fnOddfact(N-1)
10130 Q=member(O,1)
10140 K=member(O,2)
10150 I=0
10160 repeat
10170 repeat
10180 X=fnLrand(N)
10190 until X>1
10200 J=0
10210 Y=modpow(X,Q,N)
10220 loop
10230 if or{and{J=0,Y=1},Y=N-1} then goto *ProbPrime
10240 if and{J>0,Y=1} then goto *NotPrime
10250 J=J+1
10260 if J=K then goto *NotPrime
10270 Y=(Y*Y)@N
10280 endloop
10290 *ProbPrime
10300 I=I+1
10310 until I>50
10320 Ans=1
10330 goto *EndPrime
10340 *NotPrime
10350 Ans=0
10360 *EndPrime
10370 return(Ans)
10380 '
10400 fnLrand(N)
10410 local R
10415 N=int(N)
10420 R=(int(rnd*10^(alen(N)+2)))@N
10430 return(R)
10440 '
10500 fnNxprime(X)
10510 if X@2=0 then X=X+1
10520 while fnPrime(X)=0
10530 X=X+2
10540 wend
10550 return(X)
re: Moore's Law at work
