

A075013


Smallest k such that the decimal concatenation of k and k+1 is divisible by n.


1



1, 1, 1, 1, 4, 1, 5, 5, 4, 9, 16, 1, 7, 5, 4, 19, 3, 13, 22, 19, 16, 27, 2, 19, 24, 7, 31, 5, 31, 19, 27, 19, 16, 3, 9, 31, 26, 41, 7, 19, 28, 37, 20, 27, 4, 51, 20, 19, 16, 49, 52, 35, 32, 31, 49, 5, 22, 31, 66, 19, 32, 27, 58, 19, 9, 49, 6, 35, 28, 9, 26, 67, 13, 63, 49, 79, 16
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OFFSET

1,5


LINKS

Table of n, a(n) for n=1..77.


EXAMPLE

a(16) = 19 as 16 divides 1920.


MATHEMATICA

With[{cnct=Table[FromDigits[Flatten[IntegerDigits/@{n, n+1}]], {n, 100}]}, Table[ Position[cnct, _?(Divisible[#, k]&), 1, 1], {k, 100}]]//Flatten (* Harvey P. Dale, Apr 11 2020 *)


PROG

(PARI) for(n=1, 100, k=1:while((k*(10^floor(log(k+1)/log(10)+1))+k+1)%n>0, k=k+1):print1(k", "))


CROSSREFS

Cf. A075114, A075115, A075116, A075117.
Sequence in context: A105721 A099310 A021880 * A117379 A007309 A333341
Adjacent sequences: A075010 A075011 A075012 * A075014 A075015 A075016


KEYWORD

base,nonn


AUTHOR

Amarnath Murthy, Sep 01 2002


EXTENSIONS

Corrected and extended by Ralf Stephan, Mar 23 2003


STATUS

approved



