A129189 n-th prime + n-th composite - n.

5, 7, 10, 12, 16, 19, 24, 26, 30, 37, 40, 46, 50, 53, 57, 63, 69, 71, 78, 83, 85, 91, 95, 101, 110, 114, 116, 121, 124, 128, 142, 147, 153, 155, 165, 167, 174, 180, 184, 190, 196, 199, 210, 212, 216, 218, 230, 243, 247, 249, 254, 261, 263, 273, 279, 285, 292, 294

Offset: 1

Author

Edwin F. Sampang, Apr 01 2007

Keywords

• nonn

Examples

			n(1)=2+4-1, n(2)=3+6-2, n(3)=5+8-3, n(4)=7+9-4, n(5)=11+10-5.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

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..74); # Emeric Deutsch, Apr 16 2007

Mathematica

Module[{nn=80,prs,cmps,len},prs=Prime[Range[nn]];cmps=Complement[ Range[ 2,2nn],prs];len=Min[nn,Length[cmps]];#[[1]]+#[[2]]-#[[3]]&/@ Thread[ {Take[ prs,len],Take[cmps,len],Range[len]}]] (* Harvey P. Dale, Oct 05 2016 *)

Formula

a(n) = A064799(n) - n. - Michel Marcus, Mar 14 2014

Extensions

More terms from Emeric Deutsch, Apr 16 2007