A088823 a(n) is the GCD of the sum of largest prime factors of numbers from 1 to n and of the sum of smallest prime factors of numbers from 1 to n.

0, 2, 5, 7, 12, 1, 1, 1, 1, 4, 1, 1, 1, 2, 1, 1, 6, 1, 1, 1, 4, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 4, 1, 3, 1, 2, 3, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 10, 1, 1, 1, 2, 29, 1, 1, 2, 1, 7, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 3, 1, 1, 2, 1, 5, 1, 14, 1, 1

Offset

1,2

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Formula

a(n) = gcd(A088821(n), A088822(n)).

Maple

map(igcd@op, ListTools:-PartialSums([[0, 0], seq([min, max](numtheory:-factorset(n)), n=2..N)])); # Robert Israel, Dec 16 2015

Mathematica

GCD @@@ Transpose[{Accumulate[Prepend[First /@ #, 0]], Accumulate[Prepend[Last /@ #, 0]]}] &@ Map[First /@ FactorInteger@ # &, Range[2, 103]] (* Michael De Vlieger, Dec 15 2015 *)

Crossrefs

Cf. A088821, A088822, A088824, A088825.

Sequence in context: A265791 A039679 A374105 * A302294 A007445 A350129

Adjacent sequences: A088820 A088821 A088822 * A088824 A088825 A088826

Keyword

nonn

Author

Labos Elemer, Oct 22 2003

Status

approved