A308721 Locations of the first occurrence of pair (0,n) in the van Eck sequence (A181391).

0, 1, 3, 20, 24, 10, 30, 276, 388, 81, 225, 726, 2935, 1408, 7718, 5624, 5680, 85998, 26706, 546290, 1112929, 702575, 3425417, 10537360, 21301906, 217230900, 108698091, 32381774, 846522986, 851764846, 11692311325, 46163898987

Offset

0,3

Comments

a(33) = 118456929919 and a(34) = 250327022558 but we do not yet know a(32).

Links

Table of n, a(n) for n=0..31.

Example

For a(5)=10, the pair (0,5) first occurs in A181391 at element 10.

Mathematica

With[{s = Nest[# /. {{Longest[p___], a_, q___, a_} :> {p, a, q, a, Length[{a, q}]}, {a___} :> {a, 0}} &, {}, 10^3]}, TakeWhile[#, # > -1 &] &@ Array[If[Length@ # == 0, -1, #[[1, 1]] - 1 ] &@ SequencePosition[s, {0, #}] &, Max@ s, 0]] (* Michael De Vlieger, Jul 08 2019, after JungHwan Min at A181391 *)

Crossrefs

Cf. A181391.

Sequence in context: A169642 A222482 A022129 * A053748 A075358 A352810

Adjacent sequences: A308718 A308719 A308720 * A308722 A308723 A308724

Keyword

sign,more

Author

Tomas Rokicki, Jun 19 2019

Status

approved