login

Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.

a(n) is the number from which if odd-positioned digits are deleted then one gets the concatenation of first n prime numbers, while if even-positioned digits are deleted then one gets reverse concatenation of first n prime numbers. Position of least significant digit is considered to be 1.
6

%I #2 Dec 05 2013 19:55:57

%S 22,2332,253352,27355372,213157751312,2133517117151332,

%T 21375173111117351372,213951771113113117751392,

%U 2233517911171133117117952332,22395273111911371173119127352392

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

%e a(4) = 27355372: deleting alternate digits starting from the LSD leaves 2357. Deleting the other ones leaves 7532.

%Y Cf. A078279, A078280, A078281.

%K base,nonn

%O 1,1

%A _Amarnath Murthy_, Nov 25 2002

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