A121761 - OEIS

%I #4 Mar 30 2012 17:26:22

%S 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,1,6,11,16,21,26,31,

%T 36,41,46,30,31,32,33,34,35,36,37,38,39,2,7,12,17,22,27,32,37,42,47,

%U 50,51,52,53,54,55,56,57,58,59,3,8,13,18,23,28,33,38,43,48,70,71,72,73,74,75

%N In decimal number system, take negative power of 10 at even digits of n. Sequence gives numerators of result.

%C See accompanying sequence A121760 In decimal number system, take negative power of 10 at odd digits of n.

%H Zak Seidov, <a href="/A121761/b121761.txt">First 1000 terms</a>

%F If n=sum(d(i)*10^(i-1)), then a(n)=sum(d(i)*10^((-1)^(1+d(i))*(i-1)))

%e a(23)=16 because 23=2*10^1+3*10^0 and a(23)=numerator[2*10^((-1)^(1+2)*1)+3*10^((-1)^(1+3)*0)=2/10+3=32/10=16/5]=16.

%Y Cf. A121760.

%K base,frac,nonn

%O 1,2

%A _Zak Seidov_, Aug 20 2006