A256340 Numbers which have only digits 7 and 8 in base 10.

7, 8, 77, 78, 87, 88, 777, 778, 787, 788, 877, 878, 887, 888, 7777, 7778, 7787, 7788, 7877, 7878, 7887, 7888, 8777, 8778, 8787, 8788, 8877, 8878, 8887, 8888, 77777, 77778, 77787, 77788, 77877, 77878, 77887, 77888, 78777, 78778, 78787, 78788, 78877, 78878

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) + A002280(A000523(n+1)) = A256292(n) + A256077(n) etc.

Mathematica

Flatten[Table[FromDigits[#, 10]&/@Tuples[{7, 8}, n], {n, 5}]]

Prog

(Magma) [n: n in [1..35000] | Set(IntegerToSequence(n, 10)) subset {7, 8}];
(PARI) A256340(n)=vector(#n=binary(n+1)[2..-1], i, 10^(#n-i))*n~+10^#n\9*7
(Magma) [n: n in [1..100000] | Set(Intseq(n)) subset {7, 8}]; // Vincenzo Librandi, Aug 19 2016
(Python)
def a(n): return int(bin(n+1)[3:].replace('0', '7').replace('1', '8'))
print([a(n) for n in range(1, 45)]) # Michael S. Branicky, Jul 08 2021

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), A256292 (digits 6 & 7), A256341 (digits 8 & 9).

Sequence in context: A248276 A137145 A251626 * A192373 A354011 A103680

Adjacent sequences: A256337 A256338 A256339 * A256341 A256342 A256343

Keyword

nonn,base,easy

Author

M. F. Hasler, Mar 27 2015

Status

approved