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 A342260 a(n)^2 is the least square that, when written in base n, has exactly n digits n-1. 3
 3, 31, 217, 268, 8399, 29110, 711243, 4676815, 31622764, 376863606, 12638826343, 38121744938, 1511790122972, 8648472039419, 243625577528103 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,1 COMMENTS 17^(25/2) < a(17) <= 4159201115231103. - Martin Ehrenstein, Jul 10 2021 LINKS FORMULA a(n) <= n^(n+1) - 1. - Bert Dobbelaere, Apr 20 2021 EXAMPLE a(2) = 3: 3^2 = 9 is the least square with 2 binary ones: 1001; a(3) = 31: 31^2 = 961 is the least square with 3 ternary digits 2: 1022121; a(4) = 217: 217^2 = 47089 = 23133301_4; a(5) = 268: 268^2 = 71824 = 4244244_5. PROG (PARI) isok(k, n) = #select(x->(x==n-1), digits(k^2, n)) == n; a(n) = my(k=1); while (!isok(k, n), k++); k; \\ Michel Marcus, Apr 05 2021 (Python) from sympy.ntheory.factor_ import digits def A342260(n):     k = 1     while digits(k**2, n).count(n-1) != n:         k += 1     return k # Chai Wah Wu, Apr 05 2021 CROSSREFS Cf. A179895, A342545, A342546. Sequence in context: A203242 A121099 A197746 * A121147 A114654 A198151 Adjacent sequences:  A342257 A342258 A342259 * A342261 A342262 A342263 KEYWORD nonn,base,more AUTHOR Hugo Pfoertner, Apr 04 2021 EXTENSIONS a(14) from Martin Ehrenstein, Apr 17 2021 a(15) from Bert Dobbelaere, Apr 20 2021 a(16) from Martin Ehrenstein, Apr 21 2021 STATUS approved

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Last modified May 20 12:55 EDT 2022. Contains 353871 sequences. (Running on oeis4.)