A068517 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).

12, 34, 56, 78, 910, 2635, 1314, 1873, 1718, 2859, 2122, 21061, 2526, 6421, 2930, 10293, 3334, 21667, 3738, 4289, 4142, 38109, 4546, 22273, 4950, 6675, 5354, 22677, 5758, 22879, 6162, 7879, 6566, 6798, 6970, 8285, 7374, 61229, 7778, 23889, 8182

Offset

0,1

Links

Table of n, a(n) for n=0..40.

Example

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

Mathematica

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]]]]

Crossrefs

Sequence in context: A077295 A030655 A098080 * A113748 A069125 A142245

Adjacent sequences: A068514 A068515 A068516 * A068518 A068519 A068520

Keyword

nonn,base,easy

Author

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

Extensions

More terms from Sascha Kurz, Feb 12 2003

Status

approved