login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A321225 Break the infinite word 1232112321... into chunks so that the sum of the digits in the n-th chunk is n. 2
1, 2, 3, 211, 23, 2112, 3211, 2321, 12321, 123211, 232112, 321123, 21123211, 2321123, 211232112, 321123211, 232112321, 1232112321, 12321123211, 23211232112, 32112321123, 2112321123211, 232112321123, 21123211232112, 32112321123211, 23211232112321, 123211232112321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

For every n=3*k, a(n) must be divisible by 3 and is therefore a palindrome. - Ivan N. Ianakiev, Nov 01 2018

For every n=3*k, the number of digits of a(n) equals he number of digits of a(n-9)+5 and the starting/ending digits of a(n) and a(n-9) are the same. For any possible natural number m, there are five possible candidate numbers for a(3*k) that are of length m, of which only one, the palindrome, is divisible by 3. - Ivan N. Ianakiev, Nov 02 2018

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..1800

EXAMPLE

1, 2, 3, 2+1+1=4, 2+3=5, 2+1+1+2=6, 3+2+1+1=7, 2+3+2+1=8, 1+2+3+2+1=9, ... .

PROG

(PARI) getd(n) = {my(m = n % 5); if (!m, m = 1); [1, 2, 3, 2, 1][m]; }

lista(nn) = {my(k = 1); for (n=1, nn, my (s = 0, list = List(), d); while (s != n, d = getd(k); listput(list, d); s += d; k++; ); print1(fromdigits(Vec(list)), ", "); ); } \\ Michel Marcus, Nov 11 2018

CROSSREFS

Cf. A028355, A028359, A321232.

Sequence in context: A195264 A316941 A037274 * A037275 A142960 A117324

Adjacent sequences:  A321222 A321223 A321224 * A321226 A321227 A321228

KEYWORD

nonn,base

AUTHOR

Seiichi Manyama, Oct 31 2018

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 14 14:31 EDT 2019. Contains 328019 sequences. (Running on oeis4.)