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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
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 8 01:00 EST 2021. Contains 349590 sequences. (Running on oeis4.)