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 A351471 Numbers m such that the largest digit in the decimal expansion of 1/m is 5. 6
 2, 4, 8, 18, 20, 22, 32, 40, 66, 74, 80, 180, 185, 198, 200, 220, 222, 320, 396, 400, 444, 492, 660, 666, 702, 704, 738, 740, 800, 803, 876, 1800, 1818, 1845, 1848, 1850, 1875, 1912, 1980, 1998, 2000, 2200, 2220, 2222, 2409, 2424, 2466, 2849, 3075, 3200, 3212, 3276, 3960, 3996, 4000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS If k is a term, 10*k is also a term. First few primitive terms are 2, 4, 8, 18, 22, 32, 66, 74, 185, 198, 222, 396, ... 2 and 4649 are the only primes up to 2.6*10^8 (see comments in A333237). Some subsequences: {2, 22, 222, 2222, ...} = A002276 \ {0}. {66, 666, 6666, ...} = A002280 \ {0, 6}. {18, 1818, 181818, ...} = 18 * A094028. LINKS Table of n, a(n) for n=1..55. Index entries for sequences related to decimal expansion of 1/n. EXAMPLE As 1/8 = 0.125, 8 is a term. As 1/4649 = 0.000215121512151..., 4649 is a term. MATHEMATICA f[n_] := Union[ Flatten[ RealDigits[ 1/n][[1]] ]]; Select[Range@1500000, Max@ f@# == 5 &] PROG (Python) from itertools import count, islice from sympy import n_order, multiplicity def A351471_gen(startvalue=1): # generator of terms >= startvalue for m in count(max(startvalue, 1)): m2, m5 = multiplicity(2, m), multiplicity(5, m) if max(str(10**(max(m2, m5)+n_order(10, m//2**m2//5**m5))//m)) == '5': yield m A351471_list = list(islice(A351471_gen(), 10)) # Chai Wah Wu, Feb 15 2022 CROSSREFS Subsequences: A002276, A002280. Similar with largest digit k: A333402 (k=1), A341383 (k=2), A350814 (k=3), A351470 (k=4), this sequence (k=5), A351472 (k=6), A351473 (k=7), A351474 (k=8), A333237 (k=9). Cf. A333236. Sequence in context: A255999 A171719 A185178 * A229718 A246469 A092507 Adjacent sequences: A351468 A351469 A351470 * A351472 A351473 A351474 KEYWORD nonn,base AUTHOR Bernard Schott and Robert G. Wilson v, Feb 14 2022 STATUS approved

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Last modified December 4 14:48 EST 2023. Contains 367563 sequences. (Running on oeis4.)