A068517 - OEIS

%I #7 Mar 31 2012 10:22:54

%S 12,34,56,78,910,2635,1314,1873,1718,2859,2122,21061,2526,6421,2930,

%T 10293,3334,21667,3738,4289,4142,38109,4546,22273,4950,6675,5354,

%U 22677,5758,22879,6162,7879,6566,6798,6970,8285,7374,61229,7778,23889,8182

%N a(2n) = concatenation of 4n+1 and 4n+2, a(2n+1) = concatenation of the two most nearly equal numbers whose product is a(2n).

%e a(6) = 1314 = 2*3^2*73 = 18*73; a(7) = 1873.

%t conc[m_, n_] := FromDigits[Join[IntegerDigits[m], IntegerDigits[n]]]; a[n_] := If[EvenQ[n], conc[2n+1, 2n+2], l=Length[ds=Divisors[a[n-1]]]; conc[ds[[l/2]], ds[[1+l/2]]]]

%K nonn,base,easy

%O 0,1

%A Jon Kongsvold (Jon.Kongsvold(AT)idi.ntnu.no) and Martin Ystenes, Mar 19 2002

%E More terms from _Sascha Kurz_, Feb 12 2003