A129188 n + n-th prime + n-th composite.
7, 11, 16, 20, 26, 31, 38, 42, 48, 57, 62, 70, 76, 81, 87, 95, 103, 107, 116, 123, 127, 135, 141, 149, 160, 166, 170, 177, 182, 188, 204, 211, 219, 223, 235, 239, 248, 256, 262, 270, 278, 283, 296, 300, 306, 310, 324, 339, 345, 349, 356, 365, 369, 381, 389, 397
Offset: 1
Keywords
Examples
a(1)=1+2+4, a(2)=2+3+6, a(3)=3+5+8, a(4)=4+7+9.
Programs
-
Maple
c:=proc(n) if isprime(n)=false then n else fi end: C:=[seq(c(n),n=2..100)]: a:=n->ithprime(n)+C[n]+n: seq(a(n),n=1..70); # Emeric Deutsch, Apr 16 2007
-
Mathematica
prs=Prime[Range[200]]; comps=Rest[Complement[Range[prs[[-1]]], prs]]; Table[n + prs[[n]] + comps[[n]], {n, Length[prs]}] (* Harvey P. Dale, Jan 11 2011 *)
Formula
a(n) = n+A064799(n). - R. J. Mathar, Nov 25 2008