cp's OEIS Frontend

A279001 Numbers of the form (11*h+j)*11^k-1 for h,k in N and j in {2,6,7,8,10}.

%I A279001 #28 Feb 23 2025 04:51:32
%S A279001 1,5,6,7,9,12,16,17,18,20,21,23,27,28,29,31,34,38,39,40,42,45,49,50,
%T A279001 51,53,56,60,61,62,64,65,67,71,72,73,75,76,78,82,83,84,86,87,89,93,94,
%U A279001 95,97,100,104,105,106,108,109,111,115,116,117,119,122,126,127
%N A279001 Numbers of the form (11*h+j)*11^k-1 for h,k in N and j in {2,6,7,8,10}.
%C A279001 Created in a failed attempt to explain sequences J and K on page 10 of Fu and Han (2016). See A279194 and A279195. - _N. J. A. Sloane_, Dec 15 2016
%H A279001 Hao Fu and G.-N. Han, <a href="https://arxiv.org/abs/1601.04370">Computer assisted proof for Apwenian sequences related to Hankel determinants</a>, arXiv preprint arXiv:1601.04370 [math.NT], 2016.
%p A279001 isA279001 := proc(n)
%p A279001     not isA279000(n) ;
%p A279001 end proc:
%p A279001 for n from 0 to 200 do
%p A279001     if isA279001(n) then
%p A279001         printf("%d,",n) ;
%p A279001     end if;
%p A279001 end do: # _R. J. Mathar_, Dec 15 2016
%t A279001 okQ[n_] := Not @ MatchQ[IntegerDigits[n+1, 11], {___, 1|3|4|5|9, 0...}];
%t A279001 Select[Range[200], okQ] (* _Jean-François Alcover_, Feb 25 2018, after _R. J. Mathar_ *)
%o A279001 (Python)
%o A279001 from sympy import integer_log
%o A279001 def A279001(n):
%o A279001     def f(x): return n-1+sum(((m:=(x+1)//11**i)-1)//11+(m-3)//11+(m-4)//11+(m-5)//11+(m-9)//11+5 for i in range(integer_log(x+1,11)[0]+1))
%o A279001     m, k = n, f(n)
%o A279001     while m != k: m, k = k, f(k)
%o A279001     return m # _Chai Wah Wu_, Feb 23 2025
%Y A279001 Complement of A279000.
%Y A279001 Cf. A279194, A279195.
%K A279001 nonn
%O A279001 1,2
%A A279001 _N. J. A. Sloane_, Dec 07 2016
%E A279001 Corrected by _Lars Blomberg_ (base 5 replaced by base 11. 10 removed, 21 added,...), Dec 15 2016