Seq and first diff show the same "digit pattern"
Eric Angelini
Eric.Angelini at kntv.be
Mon Jul 2 17:28:54 CEST 2007
Hello SeqFan,
could someone compute a few more terms of this seq:
1 12 14 155 160 211 271 292 419 548 572 691 ...
The principle is:
- Seq and first diff show the same "digit pattern".
S = 1 12 14 155 160 211 271 292 419 548 572 691 ...
d = 11 2 141 5 51 60 21 127 129 24 19 ...
Rules:
- start S with "1"
- add to the last term of S the smallest integer d no yet
added and not present in S such that the concatenation
of S's terms and the concatenation of all ds are the
same string of digits
So, never twice the same integer in sequence or first
differences.
I'm quite sure that all N's will be split between S and d.
Best,
É.
http://www.research.att.com/~njas/sequences/A110621
has a close Mathematica pgm by Robert G. Wilson.
(thanks again to him!)
Something is wrong with my email, and I haven't been receiving all emails
have.
I will post the solution now, even though only a short while has passed
Original email as spoiler-space.
>Since people are posting sequence puzzles on seq.fan lately, I thought I
>would post this sequence puzzle of a different varity.
>
>I suspect this 'puzzle' is easy, and I'll probably regret I posted this.
>
>---
>
>Let {c(k)} be as defined at sequence A022940. ({c(k)} itself is not in
>the EIS.)
>
>Define sequence {a(k)} as follows:
>
>Let b(n) = c(n) - n + 1.
>
>a(1) = the number of 1's in {b(k)}. a(2) = the number of 2's in {b(k)}.
>In general, a(n) = the number of n's in {b(k)}.
>
>So, {a(k)} begins: 0,1,1,3,5,6,7,9,...
>
>Define {a(k)}. (Define it in a simpler way than by the steps given above.)
>
>Thanks,
>Leroy Quet
I get that a(1)=0, a(2)=1. a(n) = c(n-2) -1, for n >= 3.
I don't know if there is a "closed form" (nonrecursive representation)
for {c(k)}.
Thanks,
leroy Quet
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