OFFSET
1,2
COMMENTS
This sequence is a permutation of the positive integers.
LINKS
Ivan Neretin, Table of n, a(n) for n = 1..10000
EXAMPLE
12 has a prime-factorization of 2^2 *3^1 and the highest exponent is 2. So a(12) is the 2nd integer from among those positive integers not occurring among the first 11 terms of the sequence (i.e., the second integer from 12,13,14,...). So a(12) = 13.
MATHEMATICA
f[l_List] := Block[{k = 0, c = Max @@ Last /@ FactorInteger[Length[l] + 1]}, While[c > 0, k++; While[MemberQ[l, k], k++ ]; c--; ]; Append[l, k]]; Nest[f, {1}, 75] (* Ray Chandler, Nov 23 2006 *)
Fold[Append[#1, Complement[Range[Log2[#2] + Max[#1]], #1][[Max[FactorInteger[#2][[All, 2]]]]]] &, {1}, Range[2, 72]] (* Ivan Neretin, Aug 29 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Nov 19 2006
EXTENSIONS
Extended by Ray Chandler, Nov 23 2006
STATUS
approved