A073170 a(1) = a(2) = 0; for n>2, a(n) = prime(n-1)-n+1.

0, 0, 1, 2, 3, 6, 7, 10, 11, 14, 19, 20, 25, 28, 29, 32, 37, 42, 43, 48, 51, 52, 57, 60, 65, 72, 75, 76, 79, 80, 83, 96, 99, 104, 105, 114, 115, 120, 125, 128, 133, 138, 139, 148, 149, 152, 153, 164, 175, 178, 179, 182, 187, 188, 197, 202, 207, 212, 213, 218, 221

Offset: 1

Author

Labos Elemer, Jul 19 2002

Keywords

• nonn

Comments

Smallest x such that A002808(x)-x (cf. A073169) equals n, or 0 if no such value exists.

Crossrefs

Cf. A002808, A073168, A073169. Essentially same sequence as A014689.

Cf. A000040, A014689.

Programs

Mathematica

f[x_] := FixedPoint[x+PrimePi[ # ]+1&, x] t=Table[0, {100}]; Do[s=f[n]-n; If[s<101&&t[[s]]==0, t[[s]]=n], {n, 1, 10000}]; t
Join[{0,0},Table[Prime[n-1]-n+1,{n,3,70}]] (* Harvey P. Dale, Dec 18 2012 *)

Formula

a(n)=Min{x; composite[x]-x=n}

Extensions

Simpler description from Vladeta Jovovic, Mar 29 2003

Definition corrected by Harvey P. Dale, Dec 18 2012