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

1,1

Links

Table of n, a(n) for n=1..59.

Formula

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

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 *)

Crossrefs

Sequence in context: A201578 A322292 A195707 * A000509 A160257 A315830

Adjacent sequences: A175214 A175215 A175216 * A175218 A175219 A175220

Keyword

nonn,easy

Author

Jaroslav Krizek, Mar 06 2010

Extensions

More terms from Reinhard Zumkeller, Mar 29 2010

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

Status

approved