A175217 The second nonprimes after the primes.

6, 6, 8, 9, 14, 15, 20, 21, 25, 32, 33, 39, 44, 45, 49, 55, 62, 63, 69, 74, 75, 81, 85, 91, 99, 104, 105, 110, 111, 115, 129, 133, 140, 141, 152, 153, 159, 165, 169, 175, 182, 183, 194, 195, 200, 201, 213, 225, 230, 231, 235, 242, 243, 253, 259, 265, 272, 273, 279

Offset: 1

Author

Jaroslav Krizek, Mar 06 2010

Keywords

• nonn
• easy

Programs

Mathematica

b[n_] := Boole[PrimeQ[n]];
a[n_] := With[{p = Prime[n]}, p + 2 + b[p + 1] + b[p + 2] + b[p + 3]];
Array[a, 59] (* Jean-François Alcover, Nov 12 2017, after Reinhard Zumkeller *)

Formula

a(n) = prime(n)+2 + A010051(prime(n)+1) + A010051(prime(n)+2) + A010051(prime(n)+3). [From Reinhard Zumkeller, Mar 29 2010]

Extensions

More terms from Reinhard Zumkeller, Mar 29 2010

Typos in data corrected by Jean-François Alcover, Nov 12 2017