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

1,1

Links

Table of n, a(n) for n=1..49.

Example

{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}..

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

Crossrefs

Cf. A070865

Sequence in context: A160856 A019445 A119638 * A168674 A110935 A128034

Adjacent sequences: A178544 A178545 A178546 * A178548 A178549 A178550

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, May 29 2010

Status

approved