A126917 a(1)=1. a(n) = the (largest proper divisor of n)th integer from among those positive integers not occurring earlier in the sequence.

1, 2, 3, 5, 4, 8, 6, 11, 10, 14, 7, 17, 9, 20, 18, 23, 12, 26, 13, 29, 25, 32, 15, 35, 24, 38, 33, 41, 16, 44, 19, 47, 40, 50, 34, 53, 21, 56, 48, 59, 22, 62, 27, 65, 55, 68, 28, 71, 43, 74, 63, 77, 30, 80, 54, 83, 70, 86, 31, 89, 36, 92, 78, 95, 64, 98, 37, 101, 85, 104, 39

Offset: 1

Author

Leroy Quet, Dec 31 2006

Keywords

• nonn

Comments

Sequence is a permutation of the positive integers.

Examples

			The largest proper divisor of 8 is 4. So a(8) is the 4th integer from among those not occurring among the first 7 integers of the sequence (a(8) is the 4th integer from among 7,9,10,11,13,14,..). So a(8) = 11.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A126918, A032742, A243069, A243488.

Programs

Mathematica

f[l_List] := Block[{k = 0, c = Divisors[Length[l] + 1][[ -2]]},While[c > 0,k++;While[MemberQ[l, k], k++ ];c--;];Append[l, k]];Nest[f, {1}, 71] (* Ray Chandler, Jan 04 2007 *)

Extensions

Extended by Ray Chandler, Jan 04 2007