A078269 a(n) is the number from which if odd-positioned digits are deleted then one gets the concatenation of 1 to n, while if even-positioned digits are deleted then one gets reverse concatenation of 1 to n. Position of least significant digit is considered to be 1.

11, 1221, 132231, 14233241, 1524334251, 162534435261, 17263544536271, 1827364554637281, 192837465564738291, 1120394857667584931201, 11213140596877869514031211, 112231415160798897160514131221

Offset

1,1

Links

Table of n, a(n) for n=1..12.

Example

a(4) = 14233241: deleting alternate digits starting with least significant digit gives 1234 etc.

Crossrefs

Cf. A078270, A078271.

Sequence in context: A274766 A261138 A259937 * A015009 A068326 A001323

Adjacent sequences: A078266 A078267 A078268 * A078270 A078271 A078272

Keyword

base,nonn

Author

Amarnath Murthy, Nov 24 2002

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 19 2003

Status

approved