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 A309023 For n >= 1, if there exists an m < n such that a(m) = a(n), take the largest such m and set a(n+1) = (n-m)^a(n); otherwise a(n+1) = 0. Start with a(1)=1, a(2)=2. 0
 1, 2, 0, 0, 1, 4, 0, 1, 3, 0, 1, 3, 27, 0, 1, 4, 10000, 0, 1, 4, 256, 0, 1, 4, 256 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS This sequence quickly generates terms of immense size. Changing what a(n+1) is set to when a new term arises changes the sequence nontrivially. LINKS MATHEMATICA Nest[Function[{a, n}, Append[a, If[Length@ # == 0, 0, (n - #[[-1, 1]])^Last@ a] &@ Position[Most@ a, _?(# == Last@ a &)] ]] @@ {#, Length@ #} &, {1, 2}, 24] (* Michael De Vlieger, Jul 08 2019 *) PROG (Python) def Prog(length):     L = 2     seq = [1, 2]     while L < length:         x = len(seq)-1         while x > 0:             if seq[-1] == seq[x-1]:                 m_minus_n = len(seq)-x                 a_n = seq[L-1]                 seq.append((m_minus_n)**a_n)                 x = -1             else:                 x -= 1             if x == 0:                 seq.append(0)         L += 1     return seq CROSSREFS Cf. A181391. Sequence in context: A168511 A111146 A109077 * A137585 A301344 A301579 Adjacent sequences:  A309020 A309021 A309022 * A309024 A309025 A309026 KEYWORD nonn AUTHOR Philip Kalisman, Jul 07 2019 STATUS approved

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Last modified January 20 01:01 EST 2022. Contains 350467 sequences. (Running on oeis4.)