A078279 a(n) is the number from which if odd-positioned digits are deleted then one gets the concatenation of first n composite numbers, while if even-positioned digits are deleted then one gets reverse concatenation of first n composite numbers. Position of least significant digit is considered to be 1.

44, 4664, 486684, 49688694, 416089981604, 4162819019081624, 41648192110019281644, 416581941102112019481654, 4166819511041122114019581664, 41688196110511241142115019681684

Offset

1,1

Links

Table of n, a(n) for n=1..10.

Example

a(4) = 49688694: deleting alternate digits starting from the LSD leaves 4689. Deleting the other ones leaves 9864.

Crossrefs

Cf. A078278, A078280, A078281.

Sequence in context: A220599 A304460 A332562 * A268548 A203974 A266853

Adjacent sequences: A078276 A078277 A078278 * A078280 A078281 A078282

Keyword

base,nonn

Author

Amarnath Murthy, Nov 25 2002

Extensions

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

Status

approved