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

4, 5, 44, 45, 54, 55, 444, 445, 454, 455, 544, 545, 554, 555, 4444, 4445, 4454, 4455, 4544, 4545, 4554, 4555, 5444, 5445, 5454, 5455, 5544, 5545, 5554, 5555, 44444, 44445, 44454, 44455, 44544, 44545, 44554, 44555, 45444, 45445, 45454, 45455, 45544

Offset

1,1

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..8190

Index entries for 10-automatic sequences.

Formula

a(n) = A007931(n) + A002277(A000523(n+1)) = A032834(n) + A256077(n) etc.

Mathematica

Flatten[Table[FromDigits[#, 10]&/@Tuples[{4, 5}, n], {n, 5}]]

Prog

(Magma) [n: n in [1..60000] | Set(IntegerToSequence(n, 10)) subset {5, 4}];
(PARI) A256290(n)=vector(#n=binary(n+1)[2..-1], i, 10^(#n-i))*n~+10^#n\9*4
(Magma) [n: n in [1..100000] | Set(Intseq(n)) subset {4, 5}]; // Vincenzo Librandi, Aug 19 2016
(Python)
def A256290(n): return int(bin(n+1)[3:])+(10**((n+1).bit_length()-1)-1<<2)//9 # Chai Wah Wu, Jul 15 2023

Crossrefs

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).

Sequence in context: A123304 A270129 A271293 * A041037 A041038 A239860

Adjacent sequences: A256287 A256288 A256289 * A256291 A256292 A256293

Keyword

nonn,base,easy

Author

M. F. Hasler, Mar 27 2015

Status

approved