A114403 Triprime gaps. First differences of A014612.

4, 6, 2, 7, 1, 2, 12, 2, 1, 5, 2, 11, 3, 2, 2, 5, 1, 2, 14, 6, 1, 3, 3, 5, 4, 2, 1, 7, 1, 5, 8, 9, 1, 5, 1, 10, 1, 5, 1, 1, 2, 1, 7, 4, 2, 2, 5, 12, 5, 10, 8, 1, 5, 2, 4, 2, 1, 1, 9, 3, 3, 5, 2, 5, 2, 4, 3, 2, 1, 1, 4, 2, 18, 6, 2, 4, 3, 7, 1, 5, 5, 2, 9, 2, 1

Offset

1,1

Links

T. D. Noe, Table of n, a(n) for n=1..10000

Formula

a(n) = A014612(n+1) - A014612(n).

Example

a(1) = 4 = 12-8 where 8 is the first triprime and 12 is the second.
a(2) = 6 = 18-12
a(3) = 2 = 20-18
a(4) = 7 = 27-20

Maple

is3Alm := proc(n::integer) local ifa, ex, i ; ifa := op(2, ifactors(n)) ; ex := 0 ; for i from 1 to nops(ifa) do ex := ex+ op(2, op(i, ifa)) ; od : if ex = 3 then RETURN(true) ; else RETURN(false) ; fi ; end: A014612 := proc(n::integer) local resul, i; i :=1; resul := 8 ; while i < n do resul := resul + 1 ; if is3Alm(resul) then i := i+1 ; fi ; od ; RETURN(resul) ; end: A114403 := proc(n::integer) RETURN(A014612(n+1)-A014612(n)) ; end: for n from 1 to 160 do printf("%d, ", A114403(n)) ; od: # R. J. Mathar, Apr 25 2006

Mathematica

Differences[Select[Range[425], PrimeOmega[#] == 3 &]] (* Jayanta Basu, Jul 01 2013 *)

Crossrefs

Cf. A014612, A065516, A111870, A111871, A114403-A114411, A114412-A114422.

Sequence in context: A236189 A347910 A342875 * A356763 A137662 A336049

Adjacent sequences: A114400 A114401 A114402 * A114404 A114405 A114406

Keyword

easy,nonn

Author

Jonathan Vos Post, Nov 25 2005

Extensions

Corrected and extended by R. J. Mathar, Apr 25 2006

Status

approved