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A334620
a(n) is the smallest multiple of n formed by the concatenation 1,2,3,...,k for some k.
1
1, 12, 12, 12, 12345, 12, 1234567891011, 123456, 12345678, 12345678910, 123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106, 12
OFFSET
1,2
LINKS
FORMULA
a(n) is the smallest multiple of n appearing in A007908.
EXAMPLE
a(3) = 12, because 12 is the smallest multiple of 3 that appears in A007908.
MAPLE
f:= proc(n) local x, i;
x:= 0;
for i from 1 do
x:= x*10^(1+ilog10(i))+i;
if x mod n = 0 then return x fi
od
end proc:
map(f, [$1..20]); # Robert Israel, Oct 25 2020
MATHEMATICA
smn[n_]:=Module[{k=1, c=1}, While[!Divisible[c, n], k++; c= c*10^IntegerLength[ k]+ k]; c]; Array[ smn, 20] (* Harvey P. Dale, Apr 04 2022 *)
PROG
(PARI) a(n) = j=""; for(k=1, oo, j=eval(concat(Str(j), k)); if(j%n==0, return(j)))
CROSSREFS
Sequence in context: A056627 A376820 A376819 * A061074 A372219 A064161
KEYWORD
nonn,base,easy
AUTHOR
Eder Vanzei, Sep 09 2020
STATUS
approved