1,1

Also, a(n) = binary representation of A020522(n), for n>0 (See example).

a(n) = (10^(2n) - 10^n)/9 = A002275(n)*10^n. - Omar E. Pol (info(AT)polprimos.com), Apr 16 2008

n ... A020522(n) ..... a(n)

1 ....... 2 ........... 10

2 ...... 12 .......... 1100

3 ...... 56 ......... 111000

4 ..... 240 ........ 11110000

5 ..... 992 ....... 1111100000

6 .... 4032 ...... 111111000000

7 ... 16256 ..... 11111110000000

Cf. A020522, A138144, A138145, A138720.

Adjacent sequences: A138144 A138145 A138146 this_sequence A138148 A138149 A138150

Sequence in context: A133383 A071672 A122230 this_sequence A036058 A001155 A001391

Cf. A002275.

easy,nonn

Omar E. Pol (info(AT)polprimos.com), Mar 29 2008