A263623 a(1)=1; thereafter, a(n) = smallest k such that the decimal concatenation [a(n-2)+1 a(n-2)+2, ... a(n-1)] divides the decimal concatenation [a(n-1)+1 a(n-1)+2 ... k].

1, 2, 4, 8, 36

Offset

1,2

Comments

a(6), if it exists, is > 10^6. - Lars Blomberg, Dec 01 2016

a(6) <= 86794654347484748866500883685475458354620023089553379437308257589024531796179370608623026912768. - Max Alekseyev, Dec 25 2024

Links

Table of n, a(n) for n=1..5.

Example

n=3: a(3) = 4 because k=4 is the smallest number such that 2 divides the concatenation 345...k.
n=4: a(4) = 8 because k=8 is the smallest number such that 34 divides the concatenation 567...k. See A002782 for the relevant concatenations.

Crossrefs

Cf. A002782, A029455, A332580.

Sequence in context: A094334 A138744 A243547 * A070897 A180154 A320025

Adjacent sequences: A263620 A263621 A263622 * A263624 A263625 A263626

Keyword

nonn,base,hard,more,changed

Author

N. J. A. Sloane, Oct 23 2015

Status

approved