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 A252481 Numbers whose set of digits is simply connected to 1. 0
 1, 10, 11, 12, 21, 100, 101, 102, 110, 111, 112, 120, 121, 122, 123, 132, 201, 210, 211, 212, 213, 221, 231, 312, 321, 1000, 1001, 1002, 1010, 1011, 1012, 1020, 1021, 1022, 1023, 1032, 1100, 1101, 1102, 1110, 1111, 1112, 1120, 1121, 1122, 1123, 1132, 1200, 1201, 1202, 1203, 1210, 1211, 1212, 1213, 1220, 1221, 1222, 1223 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS "Simply connected" means that there must not be a "hole" in the set of digits. E.g., {1,2,4} would not be allowed since '3' is missing. LINKS Table of n, a(n) for n=1..59. PROG (PARI) is(n)={d=Set(digits(n)); d[1]==1 || (#d>1&&d[2]==1) || return; d[#d]==#d-!d[1]} (Python) def ok(n): s = set(str(n)); return '1' in s and len(s) == ord(max(s))-ord(min(s))+1 def aupto(nn): return [m for m in range(1, nn+1) if ok(m)] print(aupto(1223)) # Michael S. Branicky, Jan 10 2021 CROSSREFS Cf. A032981, A050278, A033075, A010785, A108965, A134336, A252490. Sequence in context: A362987 A235828 A102695 * A308854 A144582 A048024 Adjacent sequences: A252478 A252479 A252480 * A252482 A252483 A252484 KEYWORD nonn,base AUTHOR M. F. Hasler, Dec 24 2014 STATUS approved

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Last modified September 24 17:02 EDT 2023. Contains 365579 sequences. (Running on oeis4.)