A277680 Inverse of the permutation A277679 of the natural numbers.

1, 3, 2, 5, 6, 8, 4, 10, 9, 12, 13, 19, 7, 14, 15, 17, 11, 21, 18, 25, 26, 32, 16, 27, 20, 23, 24, 34, 33, 40, 28, 30, 22, 36, 35, 38, 41, 51, 31, 42, 43, 49, 39, 53, 50, 61, 62, 72, 29, 44, 45, 47, 37, 55, 48, 63, 64, 70, 46, 65, 52, 59, 60, 74, 73, 84, 54

Offset: 1

Author

Clark Kimberling, Nov 14 2016

Keywords

• nonn
• look
• easy

Comments

This is a permutation of the natural numbers, with inverse permutation A277679.

Links

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

Crossrefs

Cf. A000027, A277679, A007062, A057030.

Programs

Mathematica

x = Range[500];
NestWhile[# + 1 &, 1, (t = 1/2 # (1 + #);
x = Flatten[{Take[x, t],
Map[Reverse, Partition[Drop[x, t], # + 1]]}];
Length[x] > t) &]; x (* A277679 *)
Take[Ordering[#],Position[Differences[Sort[#]],Except[1]][[2]][[1]]]&[x] (* A277680 *) (* Peter J. C. Moses, Nov 13 2016 *)