A076607 a(0)=1 and for n>0: a(n) = if gcd(a(n-1),n)>1 then lcm(a(n-1),n) else a(n-1)+n.

1, 2, 2, 5, 9, 14, 42, 42, 168, 504, 2520, 2531, 2543, 2556, 17892, 89460, 357840, 357857, 357875, 357894, 3578940, 25052580, 275578380, 275578403, 275578427, 275578452, 3582519876, 10747559628, 75232917396, 75232917425, 451397504550

Offset

0,2

Comments

As gcd(a(7-1),7) = gcd(42,7) = 7, a(7) = lcm(a(7-1),7) = a(6)*7/gcd(a(7-1),7) = 42*7/7 = 42 = a(6), are there more n such that a(n+1)=a(n)?

Links

Robert Israel, Table of n, a(n) for n = 0..1145

Maple

A[0]:= 1:
for n from 1 to 100 do
  if igcd(A[n-1], n) > 1 then A[n]:= ilcm(A[n-1], n)
  else A[n]:= A[n-1]+n
  fi
od:
seq(A[i], i=0..100); # Robert Israel, Apr 18 2019

Crossrefs

Sequence in context: A184296 A131133 A096569 * A325104 A054229 A212812

Adjacent sequences: A076604 A076605 A076606 * A076608 A076609 A076610

Keyword

nonn

Author

Reinhard Zumkeller, Oct 21 2002

Extensions

Corrected by Robert Israel, Apr 18 2019

Status

approved