OFFSET
1,1
COMMENTS
a(n) is also the initial digit of n-th perfect number A000396(n) if there are no odd perfect numbers.
LINKS
Omar E. Pol, Los nĂºmeros perfectos, (in Spanish).
EXAMPLE
a(5) = 3 because the 5th even perfect number is 33550336 and the initial digit of 33550336 is 3.
MATHEMATICA
lst = {* the list of terms in A000043 *}; f[n_] := Block[{pn = (2^n - 1) (2^(n - 1))}, Quotient[pn, 10^Floor[ Log[10, pn]] ]]; f@# & /@ lst (* Robert G. Wilson v, Apr 01 2008 *)
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Omar E. Pol, Mar 01 2008
EXTENSIONS
More terms from Robert G. Wilson v, Apr 01 2008
Definition clarified by Omar E. Pol, Apr 14 2018
a(40)-a(47) from Ivan Panchenko, Apr 16 2018
a(48) from Amiram Eldar, Oct 16 2024
STATUS
approved