A049073 LCM of all divisors of d of n such that d+1 is a prime power.

1, 2, 3, 4, 1, 6, 7, 8, 3, 10, 1, 12, 1, 14, 15, 16, 1, 18, 1, 20, 21, 22, 1, 24, 1, 26, 3, 28, 1, 30, 31, 16, 3, 2, 7, 36, 1, 2, 3, 40, 1, 42, 1, 44, 15, 46, 1, 48, 7, 10, 3, 52, 1, 18, 1, 56, 3, 58, 1, 60, 1, 62, 63, 16, 1, 66, 1, 4, 3, 70, 1, 72, 1, 2, 15, 4, 7, 78, 1, 80, 3, 82, 1, 84, 1

Offset: 1

Author

David E. Daykin

Keywords

• nonn
• easy
• nice

Comments

a(A185208(n)) = 1. - Reinhard Zumkeller, Nov 01 2012

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• Index entries for sequences related to lcm's

Crossrefs

Cf. A141197, A027750, A010055.

Programs

Haskell

a049073 = foldl lcm 1 . filter ((== 1) . a010055 . (+ 1)) . a027750_row
-- Reinhard Zumkeller, Nov 01 2012

Mathematica

a[n_] := LCM @@ Select[Divisors[n], PrimeNu[# + 1] == 1 &]; Table[a[n], {n, 1, 85}] (* Jean-François Alcover, Aug 17 2013 *)

Extensions

More terms from Erich Friedman, Jun 03 2001