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 A340258 Lexicographically earliest sequence of distinct positive terms such that for any n > 0, n + a(n) is digitally balanced. 1
 1, 7, 6, 5, 4, 3, 2, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 28, 106, 105, 104, 103, 102, 101, 100, 99, 98, 97, 96, 95, 94, 93, 92, 91, 90, 89, 88, 87, 86, 85, 84, 83, 82, 81, 80, 79, 78, 77, 76, 75, 74, 73, 72, 71, 70, 69 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Digitally balanced numbers correspond to A031443. This sequence is a self-inverse permutation of the natural numbers. LINKS Rémy Sigrist, Table of n, a(n) for n = 1..10000 Rémy Sigrist, PARI program for A340258 Index entries for sequences that are permutations of the natural numbers EXAMPLE The first terms, alongside the binary representation of n + a(n), are: n a(n) bin(n + a(n)) -- ---- ------------- 1 1 10 2 7 1001 3 6 1001 4 5 1001 5 4 1001 6 3 1001 7 2 1001 8 27 100011 9 26 100011 10 25 100011 11 24 100011 12 23 100011 13 22 100011 PROG (PARI) See Links section. (Python) def aupto(n): alst, aset = [], set() for k in range(1, n+1): ak = 1 while True: while ak in aset: ak += 1 binakplusk = bin(ak+k)[2:] if binakplusk.count("0")==binakplusk.count("1"): break ak += 1 alst.append(ak) aset.add(ak) return alst print(aupto(66)) # Michael S. Branicky, Jan 02 2021 CROSSREFS Cf. A031443, A306993 (multiplicative variant). Sequence in context: A333884 A055118 A132671 * A074921 A182209 A120634 Adjacent sequences: A340255 A340256 A340257 * A340259 A340260 A340261 KEYWORD nonn,base AUTHOR Rémy Sigrist, Jan 02 2021 STATUS approved

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Last modified June 16 15:23 EDT 2024. Contains 373432 sequences. (Running on oeis4.)