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A032829
Numbers whose set of base-5 digits is {3,4}.
2
3, 4, 18, 19, 23, 24, 93, 94, 98, 99, 118, 119, 123, 124, 468, 469, 473, 474, 493, 494, 498, 499, 593, 594, 598, 599, 618, 619, 623, 624, 2343, 2344, 2348, 2349, 2368, 2369, 2373, 2374, 2468, 2469, 2473, 2474, 2493, 2494, 2498
OFFSET
1,1
FORMULA
a(1)=3, a(2)=4; a(n) = 5*a(floor(n/2))+3 for n odd, otherwise a(n) = 5*a(floor((n-1)/2))+4. - Bruno Berselli, May 30 2012
MATHEMATICA
Flatten[Table[FromDigits[#, 5]&/@Tuples[{3, 4}, n], {n, 5}]] (* Vincenzo Librandi, May 29 2012 *)
PROG
(Magma) [n: n in [1..2800] | Set(IntegerToSequence(n, 5)) subset {3, 4}]; // Vincenzo Librandi, May 29 2012
(Maxima) a[1]:3$ a[2]:4$ a[n]:= if oddp(n) then 5*a[floor(n/2)]+3 else 5*a[floor((n-1)/2)]+4$ makelist(a[n], n, 1, 45); /* Bruno Berselli, May 30 2012 */
CROSSREFS
Cf. A007091.
Sequence in context: A296283 A051473 A039563 * A039585 A025118 A025094
KEYWORD
nonn,base,easy
STATUS
approved