A013638 a(n) = prevprime(n)*nextprime(n).

10, 15, 21, 35, 55, 77, 77, 77, 91, 143, 187, 221, 221, 221, 247, 323, 391, 437, 437, 437, 551, 667, 667, 667, 667, 667, 713, 899, 1073, 1147, 1147, 1147, 1147, 1147, 1271, 1517, 1517, 1517, 1591, 1763, 1927

Offset: 3

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 3..10000

Crossrefs

Cf. A151799, A151800, A030664.

Programs

Haskell

a013638 n = a151799 n * a151800 n  -- Reinhard Zumkeller, May 22 2015

Maple

[ seq(prevprime(i)*nextprime(i),i=3..70) ];

Mathematica

a[n_] := NextPrime[n, -1] NextPrime[n];
Table[a[n], {n, 3, 50}] (* Jean-François Alcover, Aug 02 2018 *)

Formula

a(n) = A151799(n)*A151800(n). - Reinhard Zumkeller, May 22 2015