A191975 Least common multiple of all p-1, where prime p divides the n-th primary pseudoperfect number A054377(n).

1, 2, 6, 42, 330, 235290, 310800, 1863851053628494074457830

Offset

1,2

Comments

a(n) is a factor of any exponent k > 0 such that 1^k + 2^k + ... + p^k == 1 (mod p), where p = A054377(n).

Links

Table of n, a(n) for n=1..8.

J. Sondow and K. MacMillan, Reducing the Erdős-Moser equation 1^n + 2^n + ... + k^n = (k+1)^n modulo k and k^2, Integers 11 (2011), #A34.

Formula

a(n) = lcm(p-1 : prime p | A054377(n)).

Example

A054377(3) = 42 = 2*3*7, so a(3) = lcm(2-1, 3-1, 7-1) = lcm(1,2,6) = 6.

Crossrefs

Cf. A054377.

Sequence in context: A353994 A151333 A190626 * A074015 A074021 A364407

Adjacent sequences: A191972 A191973 A191974 * A191976 A191977 A191978

Keyword

nonn,more,hard

Author

Kieren MacMillan, Jun 20 2011

Status

approved