A204676 a(n) = n! * (prime(n+1) + prime(n)) / (prime(n+1) - prime(n)).

5, 8, 36, 108, 1440, 5400, 90720, 423360, 3144960, 108864000, 452390400, 9340531200, 261534873600, 1961511552000, 21794572800000, 390558744576000, 21341245685760000, 136583972388864000, 4196755964104704000, 175168944588718080000

Offset

1,1

Comments

For n >= 3 digital roots of terms appear to be equal 9, which means terms are divisible by 9. - Alexander R. Povolotsky, Jun 17 2012

Links

G. C. Greubel, Table of n, a(n) for n = 1..445

Index to divisibility sequences

Mathematica

Table[n! (Prime[n+1] + Prime[n])/(Prime[n+1] - Prime[n]), {n, 20}] (* T. D. Noe, Jan 18 2012 *)

Prog

(PARI) for(n=1, 25, print1(n! * (prime(n+1) + prime(n)) / (prime(n+1) - prime(n)), ", ")) \\ G. C. Greubel, Feb 25 2017

Crossrefs

Sequence in context: A032790 A187997 A188065 * A219947 A075273 A176859

Adjacent sequences: A204673 A204674 A204675 * A204677 A204678 A204679

Keyword

nonn

Author

Alexander R. Povolotsky, Jan 18 2012

Status

approved