%I #18 Aug 07 2019 12:57:42
%S 0,1,2,3,4,5,6,7,8,9,0,2,4,6,8,10,12,14,16,18,0,3,6,9,12,15,18,21,24,
%T 27,0,4,8,12,16,20,24,28,32,36,0,5,10,15,20,25,30,35,40,45,0,6,12,18,
%U 24,30,36,42,48,54,0,7,14,21,28,35,42,49,56,63,0,8,16,24,32,40,48,56,64,72,0
%N Product of the two numbers formed by alternate digits of n.
%H M. F. Hasler, <a href="/A080464/b080464.txt">Table of n, a(n) for n = 10..10000</a>
%F a(n) < n for all n. - _M. F. Hasler_, Jan 10 2016
%e a(132546) = 124 * 356 = 44144.
%t nad[n_]:=Module[{idn=IntegerDigits[n]},FromDigits[Take[idn,{1,-1,2}]] FromDigits[ Take[idn,{2,-1,2}]]]; Array[nad,120,10] (* _Harvey P. Dale_, Aug 07 2019 *)
%o (PARI) A080464(n,d=digits(n))={n=d*matrix(#d,2,z,s,if((z-s)%2,10^((#d-z)\2)));n[1]*n[2]}
%Y Cf. A007954, A080463, A080465, A087471, A087472, A087473, A087474.
%K base,easy,nonn,look
%O 10,3
%A _Amarnath Murthy_, Mar 02 2003
%E More terms from _Ray Chandler_, Oct 11 2003
|