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 A178547 Composite numbers; start sequence with composite number and end with prime, length of successive sequences are strictly increasing. 1
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified December 6 18:41 EST 2023. Contains 367614 sequences. (Running on oeis4.)