A256292 Numbers which have only digits 6 and 7 in base 10.

6, 7, 66, 67, 76, 77, 666, 667, 676, 677, 766, 767, 776, 777, 6666, 6667, 6676, 6677, 6766, 6767, 6776, 6777, 7666, 7667, 7676, 7677, 7766, 7767, 7776, 7777, 66666, 66667, 66676, 66677, 66766, 66767, 66776, 66777, 67666, 67667

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) + A002279(A000523(n+1)) = A256291(n) + A256077(n) etc.

Mathematica

Flatten[Table[FromDigits[#, 10]&/@Tuples[{6, 7}, n], {n, 5}]]

Prog

(Magma) [n: n in [1..35000] | Set(IntegerToSequence(n, 10)) subset {7, 6}];
(PARI) A256292(n)=vector(#n=binary(n+1)[2..-1], i, 10^(#n-i))*n~+10^#n\9*6
(Magma) [n: n in [1..100000] | Set(Intseq(n)) subset {6, 7}]; // Vincenzo Librandi, Aug 19 2016

Crossrefs

Cf. A007088 (digits 0 & 1), A007931 (digits 1 & 2), A032810 (digits 2 & 3), A032834 (digits 3 & 4), A256290 (digits 4 & 5), A256291 (digits 5 & 6), A256340 (digits 7 & 8), A256341 (digits 8 & 9).

Sequence in context: A179885 A217548 A335734 * A042877 A219517 A232008

Adjacent sequences: A256289 A256290 A256291 * A256293 A256294 A256295

Keyword

nonn,base,easy

Author

M. F. Hasler, Mar 27 2015

Status

approved