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A294952 Triangle read by rows: T(n,k) is the number of n-digit numbers having a k-digit greatest prime factor.

%I A294952 #14 Nov 24 2017 21:20:12
%S A294952 9,36,54,95,470,335,197,2854,3547,2402,356,13370,31999,25577,18698,
%T A294952 579,54250,236147,256465,199403,153156,882,196729,1486448,2386859,
%U A294952 1999848,1633601,1295633,1272,653419,8615121,19298617,19999102,16384481,13828384,11219604
%N A294952 Triangle read by rows: T(n,k) is the number of n-digit numbers having a k-digit greatest prime factor.
%C A294952 By convention, gpf(1) = 1; see A006530.
%H A294952 Charles R Greathouse IV, <a href="/A294952/b294952.txt">Table of n, a(n) for n = 1..66</a>
%e A294952 Table begins
%e A294952      9;
%e A294952     36,     54;
%e A294952     95,    470,     335;
%e A294952    197,   2854,    3547,     2402;
%e A294952    356,  13370,   31999,    25577,    18698;
%e A294952    579,  54250,  236147,   256465,   199403,  153156;
%e A294952    882, 196729, 1486448,  2386859,  1999848,  1633601,  1295633;
%e A294952   1272, 653419, 8615121, 19298617, 19999102, 16384481, 13828384, 11219604;
%o A294952 (PARI) row(n)=if(n<2, return([9])); my(v=vector(n)); forfactored(k=10^(n-1),10^n-1, v[#Str(vecmax(k[2][,1]))]++); v \\ _Charles R Greathouse IV_, Nov 12 2017
%Y A294952 Cf. A006530.
%Y A294952 First column gives A085630.
%K A294952 nonn,base,tabl
%O A294952 1,1
%A A294952 _Jon E. Schoenfield_, Nov 11 2017