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A308721 Locations of the first occurrence of pair (0,n) in the van Eck sequence (A181391). 2
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 (list; graph; refs; listen; history; text; internal format)
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 A002461

Adjacent sequences:  A308718 A308719 A308720 * A308722 A308723 A308724

KEYWORD

sign,more

AUTHOR

Tomas Rokicki, Jun 19 2019

STATUS

approved

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Last modified August 11 03:22 EDT 2020. Contains 336421 sequences. (Running on oeis4.)