1,2

248 is the number of dimensions of E_8.

a(n) has n digits.

The structure of divisors of 248 (see A018355)

..................................................................

n ............ Divisor . Formula ....... Divisor written in base 2

..................................................................

1) ................. 1 = 2^0 ........... 1

2) ................. 2 = 2^1 ........... 10

3) ................. 4 = 2^2 ........... 100

4) A134708(3) = .... 8 = 2^3 ........... 1000

5) A000668(3) = ... 31 = 2^5 - 2^0 ..... 11111

6) ................ 62 = 2^6 - 2^1 ..... 111110

7) ............... 124 = 2^7 - 2^2 ..... 1111100

8) A133028(3) = .. 248 = 2^8 - 2^3 ..... 11111000

Perfect number divided by 2: A133028. Cf. A000043, A000396, A000668, A018355, A090748, A134708, A135653.

Sequence in context: A011557 A138825 A138824 this_sequence A145442 A033146 A118256

Adjacent sequences: A138820 A138821 A138822 this_sequence A138824 A138825 A138826

easy,fini,full,nonn

Omar E. Pol (info(AT)polprimos.com), Mar 31 2008, corrected Apr 03 2008