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 A253415 Smallest missing number within the first n terms in A095258. 4
 2, 4, 5, 5, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 22, 22, 22, 22, 22, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 LINKS Michael De Vlieger, Table of n, a(n) for n = 2..10000 (terms 2..797 from Reinhard Zumkeller) MATHEMATICA c[_] = 0; c[1] = j = 1; u = 2; s = 3; Reap[Do[d = Divisors[s]; k = 1; While[c[d[[k]]] > 0, k++]; Set[k, d[[k]]]; Set[c[k], i]; If[k == u, While[c[u] > 0, u++]]; Sow[u]; j = k; s += k, {i, 2, 2^12}]][[-1, -1]] (* Michael De Vlieger, Jan 23 2022 *) PROG (Haskell) import Data.List (delete) a253415 n = a253415_list !! (n-2) a253415_list = f [2..] 1 where f xs z = g xs where g (y:ys) = if mod z' y > 0 then g ys else x : f xs' (z + y) where xs'@(x:_) = delete y xs z' = z + 2 -- Reinhard Zumkeller, Dec 31 2014 (Python) from itertools import islice from sympy import divisors def A253415_gen(): # generator of terms, first term is a(2) bset, m, s = {1}, 2, 3 while True: for d in divisors(s): if d not in bset: bset.add(d) while m in bset: m += 1 yield m s += d break A253415_list = list(islice(A253415_gen(), 30)) # Chai Wah Wu, Jan 25 2022 CROSSREFS Cf. A095258, A095259, A253425 (run lengths). Sequence in context: A278300 A034214 A317749 * A227401 A131813 A083038 Adjacent sequences: A253412 A253413 A253414 * A253416 A253417 A253418 KEYWORD nonn AUTHOR Reinhard Zumkeller, Dec 31 2014 STATUS approved

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Last modified July 16 05:19 EDT 2024. Contains 374343 sequences. (Running on oeis4.)