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

A078271

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

Terms

    a(0) =11a(1) =2112a(2) =312213a(3) =41322314a(4) =5142332415a(5) =615243342516

External references