A066310 - OEIS

%I #24 Dec 04 2024 23:04:57

%S 2,3,4,5,6,7,8,9,14,15,16,17,18,19,23,24,25,26,27,28,29,33,34,35,36,

%T 37,38,39,42,43,44,45,46,47,48,49,52,53,54,55,56,57,58,59,62,63,64,65,

%U 66,67,68,69,72,73,74,75,76,77,78,79,82,83,84,85,86,87,88,89,92,93,94,95

%N Numbers k such that k < (product of digits of k) * (sum of digits of k).

%H Harry J. Smith, <a href="/A066310/b066310.txt">Table of n, a(n) for n=1..1000</a>

%e 14 < (1*4)*(1+4) = 20, so 14 is a term of this sequence.

%e For n=199, (1+9+9)*1*9*9 = 1539 > 199, so 199 is here.

%t asum[x_] := Apply[Plus, IntegerDigits[x]] apro[x_] := Apply[Times, IntegerDigits[x]] sz[x_] := asu[x]*apro[x] Do[s=sz[n]; If[Greater[s, n], Print[n]], {n, 1, 200}]

%o (ARIBAS): function a066311(a,b: integer); var n,k,j,p,d: integer; s: string; begin for n := a to b do s := itoa(n); k := 0; p := 1; for j := 0 to length(s) - 1 do d := atoi(s[j..j]); k := k + d; p := p*d; end; if n < p*k then write(n,","); end; end; end; a066311(0,120).

%o (PARI) isok(m) = my(d=digits(m)); m < vecprod(d)*vecsum(d); \\ _Michel Marcus_, Mar 23 2020

%Y Cf. A038369, A049101-A049106, A034710, A061672, A066306-A066309.

%K base,nonn,fini

%O 1,1

%A _Labos Elemer_ and _Klaus Brockhaus_, Dec 13 2001