A099427 -id:A099427 - cp's OEIS frontend

A192489 Numbers m such that A099427(m) = 2.

2, 3, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47, 49, 53, 55, 59, 61, 67, 71, 73, 77, 79, 83, 85, 89, 91, 95, 97, 101, 103, 107, 109, 113, 115, 119, 121, 127, 131, 133, 137, 139, 143, 145, 149, 151, 155, 157, 161, 163, 167, 169, 173, 175, 179

Offset: 1

Reinhard Zumkeller, Jul 02 2011

nonn

A099427(a(n)) = 2;
primes and squares of primes greater than 9 are subsequences, cf. A000040, A001248, A000430;
GCD(A099427(a(n)-1), A099427(a(n))) = 1;
a(n) = A038179(n) for n <= 22.
The next term divisible by 3 is a(137)=429. - Joe Slater, Jan 10 2017
All terms after the first are odd, since A099427(n) == n+1 (mod 2) for n >= 3. - Robert Israel, Jan 10 2017

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

a192489 n = a192489_list !! (n-1)
a192489_list = f 2 1 where
   f n x | x' == 2   = n : f (n+1) x'
         | otherwise = f (n+1) x'
         where x' = 1 + gcd n x

A099427:= proc(n) option remember; 1 + igcd(n,procname(n-1)) end proc:
A099427(1):= 1:
select(A099427=2, [$1..1000]); # Robert Israel, Jan 10 2017

(* b = A099427 *) b[1] = 1; b[n_] := b[n] = GCD[n, b[n - 1]] + 1;
Select[Range[200], b[#] == 2&] (* Jean-François Alcover, Mar 10 2019 *)

A060401 a(n) = minimal m such that m>n, n divides m, n-1 divides m-1, n-2 divides m-2 and so on down to 1 divides m-n+1.

Original entry on oeis.org

2, 4, 9, 16, 65, 66, 427, 848, 2529, 2530, 27731, 27732, 360373, 360374, 360375, 720736, 12252257, 12252258, 232792579, 232792580, 232792581, 232792582, 5354228903, 5354228904, 26771144425, 26771144426, 80313433227, 80313433228, 2329089562829, 2329089562830

Offset: 1

Christopher Burrows (cburrows(AT)math.upenn.edu), Apr 04 2001

nonn

A099427(a(n)) = n + 1. - Reinhard Zumkeller, Jul 02 2011

			a(5) = 65 because 5|65, 4|64, 3|63, 2|62, 1|61 and 65 is minimal.

Robert Israel, Table of n, a(n) for n = 1..2296

Rightmost diagonal of triangle in A075059. Cf. A075061, A075062.

Cf. A003418.

seq(n+ilcm($1..n),n=1..100); # Robert Israel, Jul 19 2016

a(n) = n + lcm(seq(i, i=1..n)).

a(n) = n + A003418(n). - Robert Israel, Jul 19 2016

cp's OEIS Frontend

A192489 Numbers m such that A099427(m) = 2.

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