A217663 a(n) = A217662(n+2)/A217662(n) - 1, n > 0.

1, 3, 1, 5, 3, 7, 1, 3, 5, 11, 1, 13, 7, 5, 1, 17, 3, 19, 5, 1, 11, 23, 1, 5, 13, 1, 1, 29, 5, 31, 1, 11, 17, 1, 1, 37, 19, 13, 1, 41, 1, 43, 11, 1, 23, 47, 1, 1, 5, 17, 13, 53, 1, 1, 1, 1, 29, 59, 1, 61, 31, 1, 1, 13, 11, 67, 17, 23, 1, 71, 1, 73, 37, 1, 1

Offset: 1

Author

Pedja Terzic, Oct 10 2012

Keywords

• nonn

Comments

a(prime(n)-1) = prime(n) for n>1, so this sequence includes all odd primes. - Jon Perry, Oct 10 2012, edited & corrected by M. F. Hasler, Oct 11 2012

Crossrefs

Cf. A135504, A217662.

Programs

Mathematica

RecurrenceTable[{a[n]==a[n-2]+LCM[n-1,a[n-2]],a[1]==2,a[2]==2},a{n,3,51}] /RecurrenceTable[{a[n]==a[n-2]+LCM[n-1,a[n-2]],a[1]==2,a[2]==2},a,{n,1,49}]-1
t = {2, 2}; Do[AppendTo[t, t[[-2]] + LCM[n - 1, t[[-2]]]], {n, 3, 100}]; Drop[t, 2]/Drop[t, -2] - 1 (* T. D. Noe, Oct 10 2012 *)