A178547 Composite numbers; start sequence with composite number and end with prime, length of successive sequences are strictly increasing.
4, 6, 12, 20, 30, 42, 60, 80, 102, 128, 158, 192, 228, 270, 314, 360, 410, 462, 522, 588, 660, 734, 810, 888, 968, 1050, 1152, 1260, 1374, 1490, 1608, 1734, 1862, 1994, 2130, 2268, 2412, 2558, 2708, 2862, 3020, 3182, 3348, 3518, 3692, 3878, 4074, 4272, 4482
Offset: 1
Keywords
Examples
{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}..
Crossrefs
Cf. A070865
Programs
-
Mathematica
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