A131998 - OEIS

%I #5 Mar 30 2012 18:40:43

%S 5,7,10,24,33,40,44,70,78,84,90,99,105,126,132,168,176,189,190,198,

%T 208,210,231,252,306,315,340,360,368,384,391,408,420,441,462,480,520,

%U 546,575,580,598,600,608,612,638,682,693,700,702,736,740,760,770,792,814

%N Numbers n such that the number of letters in the n-th ordinal number divides n.

%C Which numbers k occur as the dividends?

%C k...smallest n such that A006944(n)/n = k.

%C 1...5.

%C 2..10.

%C 3..11

%C 4..44.

%C 5..never?

%C 6..78.

%C 7..70.

%C 8.168.

%C 9.189.

%C 10.90.

%C 11.99.

%F {n such that A006944(n)|n}.

%e a(1) = 5 because "fifth" has 5 letters.

%e a(2) = 7 because "seventh" has 7 letters.

%e a(3) = 10 because "tenth" has 5 letters and 10/5 = 2.

%e a(4) = 24 because "twentyfourth" has 12 letters and 24/12 = 2.

%e a(5) = 33 because "thirtythird" has 11 letters and 33/11 = 3.

%e a(6) = 44 because "fortyfourth" has 11 letters and 44/11 = 4.

%Y Cf. A006944, A116910.

%K easy,nonn,word

%O 1,1

%A _Jonathan Vos Post_, Oct 08 2007

%E Corrected and extended by _R. J. Mathar_, Oct 24 2007