A138823 - OEIS

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A138823

Divisors of 248 (the 3rd perfect number divided by 2), written in base 2.

1, 10, 100, 1000, 11111, 111110, 1111100, 11111000

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OFFSET

1,2

COMMENTS

248 is the number of dimensions of E_8.

a(n) has n digits.

LINKS

Table of n, a(n) for n=1..8.

Index entries for sequences related to divisors of numbers

EXAMPLE

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

MATHEMATICA

FromDigits[IntegerDigits[#, 2]]&/@Divisors[248] (* Harvey P. Dale, Apr 01 2017 *)

PROG

(PARI) divisors(248) \\ Charles R Greathouse IV, Sep 06 2016

CROSSREFS

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

Sequence in context: A290857 A290657 A286864 * A145442 A267456 A282580

Adjacent sequences: A138820 A138821 A138822 * A138824 A138825 A138826

KEYWORD

easy,fini,full,nonn,less

AUTHOR

Omar E. Pol, Mar 31 2008, corrected Apr 03 2008

STATUS

approved