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A263481 Total number of n-digit positive integers with multiplicative digital root value 8. 7

%I #28 Oct 25 2015 07:00:21

%S 1,22,138,889,4921,26687,154539,870270,4437621,20367762,86589471,

%T 388661761,2366418106,18602433227,142978182070,952075901928,

%U 5434361620523,27064481351856,120477919973804,497320625548529,2051776298637086,9590295679377844,54933121828772931

%N Total number of n-digit positive integers with multiplicative digital root value 8.

%C First differences of A263475.

%H Hiroaki Yamanouchi, <a href="/A263481/b263481.txt">Table of n, a(n) for n = 1..50</a>

%F A263476(n) + A000012(n) + A263477(n) + A000027(n) + A263478(n) + A263479(n) + A263480(n) + A000027(n) + a(n) + A000217(n) = A052268(n).

%t Last /@ Tally@ IntegerLength@ Select[Range@ 1000000, FixedPoint[Times @@ IntegerDigits@ # &, #] == 8 &] (* _Michael De Vlieger_, Oct 21 2015 *)

%o (PARI) t(k) = {while(k>9, k=prod(i=1, #k=digits(k), k[i])); k}

%o a(n) = sum(i=10^(n-1), 10^n - 1, if(t(i) == 8, 1, 0)); \\ _Altug Alkan_, Oct 19 2015

%Y Cf. A031347, A034055, A263475.

%K nonn,base

%O 1,2

%A _Martin Renner_, Oct 19 2015

%E a(9)-a(23) from _Hiroaki Yamanouchi_, Oct 25 2015

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Last modified April 25 07:07 EDT 2024. Contains 371964 sequences. (Running on oeis4.)