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A309072 a(n) is the concatenation of the initial digit of A247476(k) for k = A309063(n)..A309063(n+1)-1. 2
12132453674859161724822942, 121121, 121121, 2342536434553643455364345536436553789651617788966917178682392737988131273298, 78912142738493, 912112112192, 121121, 121121, 121121, 121121, 121121, 121121, 121121, 121121, 121121, 121121, 121121, 121121, 121121 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
For any n > 0:
- a(n) has an even number of digits,
- for any digit d appearing in a(n):
- d appears an even number of times,
- each pair of digits d is separated by d other digits,
- a(n) cannot be split into two parts with these properties.
The distribution of the first million values is as follows:
Freq. Length Value
------ ------- --------------------------------------------------------------
932062 6 121121
44451 38 78912142778498923727318198971711218297
19557 12 891211211819
3915 12 912112112192
3 14 78912142738493
1 26 12132453674859161724822942
1 76 234253643455364345536434553643..966917178682392737988131273298
1 280 789121427784989237213188991211..392931211212392931211212392131
1 712 121322432234223322432234223322..819191717881219277988131273298
1 2200 789121427784989237213188991211..392931211212392931211212392131
1 6438 121322432234223322432234223322..798916167718196687792562387539
1 64958 121322432234223322432234223322..819191717881219277988131273298
1 112810 678912162768798916167718196687..687989161677181968971711218297
1 563478 121322432234223322432234223322..177669883476364987896612172869
1 744654 678912162768798916167718196687..819191717881219277988131273298
1 2095732 789121427784989237273181989712..392931211212392931211212392131
1 5830936 234253243252332243223422332243..177669883476364987896612172869
LINKS
Rémy Sigrist, C program for A309072
EXAMPLE
For n = 2:
- A309063(2) = 27 and A309063(3)-1 = 32,
- A000030(A247476(27)) = A000030(13) = 1,
- A000030(A247476(28)) = A000030(25) = 2,
- A000030(A247476(29)) = A000030(14) = 1,
- A000030(A247476(30)) = A000030(15) = 1,
- A000030(A247476(31)) = A000030(26) = 2,
- A000030(A247476(32)) = A000030(16) = 1,
- hence a(2) = 121121.
PROG
(C) See Links section.
CROSSREFS
Sequence in context: A280347 A009190 A095444 * A217416 A358418 A133849
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Jul 10 2019
STATUS
approved

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Last modified May 28 05:47 EDT 2024. Contains 372902 sequences. (Running on oeis4.)