A087686 Elements of A004001 that repeat consecutively.

1, 2, 4, 7, 8, 12, 14, 15, 16, 21, 24, 26, 27, 29, 30, 31, 32, 38, 42, 45, 47, 48, 51, 53, 54, 56, 57, 58, 60, 61, 62, 63, 64, 71, 76, 80, 83, 85, 86, 90, 93, 95, 96, 99, 101, 102, 104, 105, 106, 109, 111, 112, 114, 115, 116, 118, 119, 120, 121, 123, 124, 125, 126, 127

Offset

1,2

Comments

Complement of A088359; A051135(a(n)) > 1. [Reinhard Zumkeller, Jun 03 2011]

From Antti Karttunen, Jan 18 2016: (Start)

This set of numbers is closed with respect to A004001, see A266188.

After 1, one more than the positions of zeros in A093879.

(End)

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Formula

Other identities. For all n >= 1:

A080677(a(n)) = n. [See comments in A080677.]

Mathematica

Conway[n_Integer?Positive] := Conway[n] =Conway[Conway[n-1]] + Conway[n - Conway[n-1]] Conway[1] = Conway[2] = 1 digits=1000 a=Table[Conway[n], {n, 1, digits}]; b=Table[If[a[[n]]-a[[n-1]]==0, a[[n]], 0], {n, 2, digits}]; c=Delete[Union[b], 1]

Prog

(Haskell)
import Data.List (findIndices)
a087686 n = a087686_list !! (n-1)
a087686_list = map succ $ findIndices (> 1) a051135_list
-- Reinhard Zumkeller, Jun 03 2011
(Scheme, with Antti Karttunen's IntSeq-library)
(define A087686 (MATCHING-POS 1 1 (lambda (n) (> (A051135 n) 1))))
;; Antti Karttunen, Jan 18 2016

Crossrefs

Cf. A004001, A051135, A093879.

Cf. A088359 (complement), A188163 (almost complement).

Cf. A080677 (the least monotonic left inverse).

Cf. also A266188, A265901, A265903, A267110, A267111, A267112.

Sequence in context: A184414 A060406 A001839 * A232054 A216431 A233271

Adjacent sequences: A087683 A087684 A087685 * A087687 A087688 A087689

Keyword

nonn

Author

Roger L. Bagula, Sep 27 2003

Status

approved