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 A335397 Starts of runs of 3 consecutive numbers that have an equal number of unitary and nonunitary divisors (A048109). 4
 22625, 28375, 40472, 48248, 49624, 58374, 59750, 102248, 103624, 107702, 112374, 129623, 136214, 136375, 164295, 187623, 190375, 197910, 199624, 211624, 221750, 246616, 264248, 275750, 280231, 298375, 300806, 312471, 346086, 349623, 352375, 356375, 372248, 382374 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Zak Seidov, Table of n, a(n) for n = 1..10000 EXAMPLE 22625 is a term since 22625, 22626 and 22627 each have an equal number of unitary and nonunitary divisors. 22625 has 4 unitary divisors (1, 125, 181 and 22625) and 4 nonunitary divisors (5, 25, 905 and 4525), 22626 has 8 unitary divisors and 8 nonunitary divisors, and 22627 has 4 unitary divisors and 4 nonunitary divisors. MATHEMATICA q[n_] := DivisorSigma[0, n] == 2^(PrimeNu[n] + 1); v = q /@ Range[3]; seq = {}; Do[v = Append[Drop[v, 1], q[k]]; If[And @@ v, AppendTo[seq, k - 2]], {k, 4, 2 * 10^5}]; seq CROSSREFS Subsequence of A048109 and A335328. Cf. A000005, A034444, A048105. Sequence in context: A233856 A100420 A271444 * A251789 A105378 A279443 Adjacent sequences: A335394 A335395 A335396 * A335398 A335399 A335400 KEYWORD nonn AUTHOR Zak Seidov and Amiram Eldar, Jun 06 2020 STATUS approved

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Last modified September 26 12:49 EDT 2023. Contains 365660 sequences. (Running on oeis4.)