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 A039145 Numbers whose base-10 representation has the same number of 4's and 9's. 1
 0, 1, 2, 3, 5, 6, 7, 8, 10, 11, 12, 13, 15, 16, 17, 18, 20, 21, 22, 23, 25, 26, 27, 28, 30, 31, 32, 33, 35, 36, 37, 38, 49, 50, 51, 52, 53, 55, 56, 57, 58, 60, 61, 62, 63, 65, 66, 67, 68, 70, 71, 72, 73, 75, 76, 77, 78, 80, 81, 82, 83, 85, 86, 87, 88, 94, 100, 101, 102 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Table of n, a(n) for n=1..69. MATHEMATICA Select[Range[0, 200], DigitCount[#, 10, 4] == DigitCount[#, 10, 9] &] (* Vincenzo Librandi, Oct 27 2016 *) PROG (Magma) [n: n in [0..120] | Multiplicity(S, 4) eq Multiplicity(S, 9) where S is {*d: d in Intseq(n)*}]; // Vincenzo Librandi, Oct 27 2016 (Python) from itertools import count, islice def A039145_gen(startvalue=0): # generator of terms >= startvalue return filter(lambda k:(s:=str(k)).count('4')==s.count('9'), count(max(startvalue, 0))) A039145_list = list(islice(A039145_gen(), 40)) # Chai Wah Wu, Mar 05 2024 CROSSREFS Sequence in context: A138309 A184514 A001068 * A242491 A038129 A062071 Adjacent sequences: A039142 A039143 A039144 * A039146 A039147 A039148 KEYWORD nonn,base,easy AUTHOR Olivier Gérard STATUS approved

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Last modified July 19 22:34 EDT 2024. Contains 374441 sequences. (Running on oeis4.)