1,2

Table of n, a(n) for n=1..66.

Index entries for sequences that are permutations of the natural numbers

a(23) = 122 because d(n) (A000005(n)) takes 121 different values before it first reaches 23 (at n = 2^22).

(Haskell)

import Data.List (elemIndex); import Data.Maybe (fromJust)

a064787 = (+ 1) . fromJust . (`elemIndex` a053212_list)

-- Reinhard Zumkeller, Apr 18 2015

Cf. A000005.

Sequence in context: A263266 A263268 A257472 * A075160 A119755 A206710

Adjacent sequences: A064784 A064785 A064786 * A064788 A064789 A064790

easy,nonn

N. J. A. Sloane, Oct 20 2001

More terms from Naohiro Nomoto, Oct 31 2001

More terms from David Wasserman, Aug 14 2002

approved