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 A256290 Numbers which have only digits 4 and 5 in base 10. 17
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..8190 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 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

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Last modified February 3 21:17 EST 2023. Contains 360045 sequences. (Running on oeis4.)