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A178547 Composite numbers; start sequence with composite number and end with prime, length of successive sequences are strictly increasing. 1

%I #2 Mar 31 2012 12:38:37

%S 4,6,12,20,30,42,60,80,102,128,158,192,228,270,314,360,410,462,522,

%T 588,660,734,810,888,968,1050,1152,1260,1374,1490,1608,1734,1862,1994,

%U 2130,2268,2412,2558,2708,2862,3020,3182,3348,3518,3692,3878,4074,4272,4482

%N Composite numbers; start sequence with composite number and end with prime, length of successive sequences are strictly increasing.

%e {004, 005} {006, 007, 008, 009, 010, 011} {012, 013, 014, 015, 016, 017, 018, 019} {020, 021, 022, 023, 024, 025, 026, 027, 028, 029} {030, 031, 032, 033, 034, 035, 036, 037, 038, 039, 040, 041}..

%t PrimeNext[n_]:=Module[{k},k=n+1;While[ !PrimeQ[k],k++ ];k]; d=0;p=2;lst={};Do[d=PrimeNext[p+d]-p;p+=d;AppendTo[lst,p+1],{n,0,5!}];lst

%Y Cf. A070865

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 29 2010

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Last modified March 1 18:30 EST 2024. Contains 370443 sequences. (Running on oeis4.)