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%I #7 Jul 11 2015 11:00:43
%S 4,14,46,141,427,1282,3849,11553,34663,104001,312005,936017,2808053,
%T 8424161,25272487,75817463,227452391,682357183,2047071551,6141214658,
%U 18423643982,55270931959,165812795887,497438387665,1492315162999
%N a(1) = 4; a(n) is smallest semiprime > 3*a(n-1).
%C Semiprime analog of A076656 a(1) = 2; a(n) is smallest prime > 3*a(n-1). a(n)-a(n-1) is often 1, never more than 16 through n = 28, then jumps to 32 for n = 29; and I wonder what its value or mean value is asymptotically as a function of n.
%t nxt[n_]:=Module[{c=3n,k=1},While[PrimeOmega[c+k]!=2,k++];c+k]; NestList[ nxt,1,30] (* _Harvey P. Dale_, May 31 2012 *)
%Y Cf. A001358, A055496, A076656.
%K easy,nonn,less
%O 1,1
%A _Jonathan Vos Post_, May 04 2006
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