A345302 a(n) = Sum_{p|n, p prime} lcm(p,n/p).

0, 2, 3, 2, 5, 12, 7, 4, 3, 20, 11, 18, 13, 28, 30, 8, 17, 24, 19, 30, 42, 44, 23, 36, 5, 52, 9, 42, 29, 90, 31, 16, 66, 68, 70, 30, 37, 76, 78, 60, 41, 126, 43, 66, 60, 92, 47, 72, 7, 60, 102, 78, 53, 72, 110, 84, 114, 116, 59, 150, 61, 124, 84, 32, 130, 198, 67, 102, 138, 210

Offset

1,2

Comments

If p is prime, a(p) = Sum_{p|p} lcm(p,p/p) = p.

Links

Table of n, a(n) for n=1..70.

Index entries for sequences related to lcm's

Example

a(12) = Sum_{p|12} lcm(p,12/p) = lcm(2,6) + lcm(3,4) = 6 + 12 = 18.

Mathematica

Table[Sum[LCM[k, n/k] (PrimePi[k] - PrimePi[k - 1]) (1 - Ceiling[n/k] + Floor[n/k]), {k, n}], {n, 100}]

Crossrefs

Cf. A008472, A057670, A345266.

Sequence in context: A343300 A285309 A250096 * A357183 A350177 A162687

Adjacent sequences: A345299 A345300 A345301 * A345303 A345304 A345305

Keyword

nonn

Author

Wesley Ivan Hurt, Jun 13 2021

Status

approved