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 A212556 Representations of nonnegative integers in base -4: The range of A007608. 1
 0, 1, 2, 3, 100, 101, 102, 103, 110, 111, 112, 113, 120, 121, 122, 123, 130, 131, 132, 133, 200, 201, 202, 203, 210, 211, 212, 213, 220, 221, 222, 223, 230, 231, 232, 233, 300, 301, 302, 303, 310, 311, 312, 313, 320, 321, 322, 323, 330, 331, 332, 333, 10000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Also: Numbers with an odd number of digits, using only digits 0 through 3. (These numbers (or strings of digits) represent nonnegative integers in base -4, while the same type of numbers with an even number of digits represent negative numbers. See references in A007608 for more information.) LINKS PROG (PARI) {forstep(d=1, 3, 2, my(u=vector(d, i, 10^(d-i))~); forvec(v=vector(d, i, [i==1 & d>1, 3]), print1(v*u", ")))} (PARI) is_A212556(n)==(#n=Str(n))%2 & !setminus(Set(Vec(n)), Vec("0123")) CROSSREFS The same as A007608 sorted in increasing order. Sequence in context: A208205 A128931 A323463 * A171460 A249409 A256114 Adjacent sequences:  A212553 A212554 A212555 * A212557 A212558 A212559 KEYWORD nonn,base AUTHOR M. F. Hasler, May 20 2012 STATUS approved

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Last modified April 10 17:00 EDT 2021. Contains 342852 sequences. (Running on oeis4.)