1,2

A139080 was only conjectured to be a permutation, until a proof has been proposed recently.

M. F. Hasler, Table of n, a(n) for n = 1..2500

OEIS Index entries of sequences related to permutations of the nonnegative integers.

(PARI) A257280=vecsort(A=A139080, , 1); for(i=1, #A, A[A257280[i]]==i||return(A257280=A257280[1..i-1]))

Sequence in context: A191732 A197393 A257271 * A050171 A258406 A136189

Adjacent sequences: A257277 A257278 A257279 * A257281 A257282 A257283

nonn

M. F. Hasler, Apr 26 2015

approved