This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A177511 #16 Sep 15 2019 07:56:43
%S A177511 3,26,62,74,77,133,134,143,155,161,185,203,206,209,215,218,319,323,
%T A177511 341,386,398,458,473,542,545,551,554,562,565,581,589,611,614,629,635,
%U A177511 662,671,695,698,703,706,707,713,718,721,889,899,913,959,965,998
%N A177511 A053735-perfect numbers.
%C A177511 For definition, see A175522.
%H A177511 Amiram Eldar, <a href="/A177511/b177511.txt">Table of n, a(n) for n = 1..10000</a>
%F A177511 {n : sum_{d|n, d<n} A053735(d) = A053735(n)}.
%p A177511 A053735 := proc(n) add(d, d=convert(n,base,3)) ;end proc:
%p A177511 isA177511 := proc(n) local a,d ; a := 0 ; for d in numtheory[divisors](n) minus {n} do a := a+A053735(d) ; end do: a = A053735(n) ;end proc:
%p A177511 for n from 1 to 1000 do if isA177511(n) then printf("%d,",n) ; end if; end do: # _R. J. Mathar_
%o A177511 (Sage) A053735 = lambda n: sum(n.digits(base=3))
%o A177511 is_A177511 = lambda n: sum(A053735(d) for d in divisors(n)) == 2*A053735(n)
%o A177511 # _D. S. McNeil_, Dec 11 2010
%o A177511 (PARI) isok(n) = sumdiv(n, d, (d<n)* vecsum(digits(d,3))) == vecsum(digits(n, 3)); \\ _Michel Marcus_, Feb 06 2016
%Y A177511 Cf. A175522, A000396, A175807, A175853, A176234, A177084, A177050.
%K A177511 nonn,base
%O A177511 1,1
%A A177511 _Vladimir Shevelev_, Dec 11 2010
%E A177511 Extended by _D. S. McNeil_, Dec 11 2010