A013638 - OEIS

%I #13 Aug 02 2018 07:43:58

%S 10,15,21,35,55,77,77,77,91,143,187,221,221,221,247,323,391,437,437,

%T 437,551,667,667,667,667,667,713,899,1073,1147,1147,1147,1147,1147,

%U 1271,1517,1517,1517,1591,1763,1927

%N a(n) = prevprime(n)*nextprime(n).

%H Reinhard Zumkeller, <a href="/A013638/b013638.txt">Table of n, a(n) for n = 3..10000</a>

%F a(n)  = A151799(n)*A151800(n). - _Reinhard Zumkeller_, May 22 2015

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

%t a[n_] := NextPrime[n, -1] NextPrime[n];

%t Table[a[n], {n, 3, 50}] (* _Jean-François Alcover_, Aug 02 2018 *)

%o (Haskell)

%o a013638 n = a151799 n * a151800 n  -- _Reinhard Zumkeller_, May 22 2015

%Y Cf. A151799, A151800, A030664.

%K nonn

%O 3,1

%A _N. J. A. Sloane_.