A191778 a(1) = 1; a(n)= 2*lcm(n, a(n - 1)).

1, 4, 24, 48, 480, 960, 13440, 26880, 161280, 322560, 7096320, 14192640, 369008640, 738017280, 1476034560, 2952069120, 100370350080, 200740700160, 7628146606080, 15256293212160, 30512586424320, 61025172848640, 2807157951037440, 5614315902074880, 56143159020748800

Offset: 1

Author

José María Grau Ribas, Jun 16 2011

Keywords

• nonn

Comments

n and a(n-1) divide a(n).

Programs

Mathematica

a[1] = 1; a[n_] := a[n]=2 LCM (n, a[n - 1]);Table[a[n],{n,100}]
RecurrenceTable[{a[1]==1,a[n]==2*LCM[n,a[n-1]]},a,{n,30}] (* Harvey P. Dale, Dec 10 2013 *)