cp's OEIS Frontend

A256290 Numbers which have only digits 4 and 5 in base 10.

%I A256290 #13 Jul 15 2023 18:28:14
%S A256290 4,5,44,45,54,55,444,445,454,455,544,545,554,555,4444,4445,4454,4455,
%T A256290 4544,4545,4554,4555,5444,5445,5454,5455,5544,5545,5554,5555,44444,
%U A256290 44445,44454,44455,44544,44545,44554,44555,45444,45445,45454,45455,45544
%N A256290 Numbers which have only digits 4 and 5 in base 10.
%H A256290 Vincenzo Librandi, <a href="/A256290/b256290.txt">Table of n, a(n) for n = 1..8190</a>
%H A256290 <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.
%F A256290 a(n) = A007931(n) + A002277(A000523(n+1)) = A032834(n) + A256077(n) etc.
%t A256290 Flatten[Table[FromDigits[#,10]&/@Tuples[{4,5},n],{n,5}]]
%o A256290 (Magma) [n: n in [1..60000] | Set(IntegerToSequence(n, 10)) subset {5, 4}];
%o A256290 (PARI) A256290(n)=vector(#n=binary(n+1)[2..-1],i,10^(#n-i))*n~+10^#n\9*4
%o A256290 (Magma) [n: n in [1..100000] | Set(Intseq(n)) subset {4,5}]; // _Vincenzo Librandi_, Aug 19 2016
%o A256290 (Python)
%o A256290 def A256290(n): return int(bin(n+1)[3:])+(10**((n+1).bit_length()-1)-1<<2)//9 # _Chai Wah Wu_, Jul 15 2023
%Y A256290 Cf. A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A032834 (digits 3 & 4), A256291 (digits 5 & 6), A256292 (digits 6 & 7), A256340 (digits 7 & 8), A256341 (digits 8 & 9).
%K A256290 nonn,base,easy
%O A256290 1,1
%A A256290 _M. F. Hasler_, Mar 27 2015