OFFSET

1,1

COMMENTS

Conjecture: Ratio of 6's to 8's approaches 1.5 as a limit as this sequence approaches infinity. - J. Lowell, Jun 26 2007

Since the best known lower bound for odd perfect numbers is ca. 10^1500, I removed all terms after a(17). - Ivan Panchenko, Sep 16 2014

REFERENCES

David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987. See p. 107.

LINKS

Math Forum at Drexel, List of Perfect Numbers.

Eric Weisstein's World of Mathematics, Perfect Number.

MAPLE

# (Maple code from N. J. A. Sloane)

# let s1 := list of terms in A000043

f:=n->if n mod 4 = 0 then 4 else n mod 4; fi; g:= x->2^f(x-1)*(2^f(x)-1); map(g, s1);

MATHEMATICA

p={ the list of the Mersenne exponents (A000043) }; Mod[(PowerMod[2, p, 10] - 1)(PowerMod[2, p - 1, 10]), 10] (* Robert G. Wilson v, May 23 2004 *)

CROSSREFS

KEYWORD

nonn,hard,base

AUTHOR

Eric W. Weisstein, May 08 2004

EXTENSIONS

STATUS

approved