cp's OEIS Frontend

A346629 Number of n-digit positive integers that are the product of two integers ending with 2.

%I A346629 #19 Aug 23 2021 06:40:27
%S A346629 1,4,45,450,4500,45000,450000,4500000,45000000,450000000,4500000000,
%T A346629 45000000000,450000000000,4500000000000,45000000000000,
%U A346629 450000000000000,4500000000000000,45000000000000000,450000000000000000,4500000000000000000,45000000000000000000,450000000000000000000
%N A346629 Number of n-digit positive integers that are the product of two integers ending with 2.
%C A346629 a(n) is the number of n-digit numbers in A139245.
%C A346629 After initial 1 or 2 values the same as A137233. - _R. J. Mathar_, Aug 23 2021
%H A346629 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (10).
%H A346629 <a href="/index/Di#digits">Index entries for sequences related to digits</a>.
%F A346629 O.g.f.: x*(1 - 6*x + 5*x^2)/(1 - 10*x).
%F A346629 E.g.f.: (9*exp(10*x) - 9 + 110*x - 50*x^2)/200.
%F A346629 a(n) = 10*a(n-1) for n > 3, with a(1) = 1, a(2) = 4 and a(3) = 45.
%F A346629 a(n) = 45*10^(n-3) for n > 2.
%F A346629 a(n) = 45*A011557(n-3) for n > 2.
%F A346629 Sum_{i=1..n} a(n) = A093143(n-1).
%t A346629 LinearRecurrence[{10},{1,4,45},25]
%Y A346629 Cf. A011557 (powers of 10), A017293 (positive integers ending with 2), A052268 (number of n-digit integers), A139245 (product of two integers ending with 2), A093143, A337855, A337856.
%Y A346629 Cf. A137233.
%K A346629 nonn,base,easy,less
%O A346629 1,2
%A A346629 _Stefano Spezia_, Jul 25 2021