A317777 -id:A317777 - cp's OEIS frontend

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A317725 a(n) is the smallest k > 1 whose sum of digits is the same in all the bases from 2 to n.

Original entry on oeis.org

2, 6, 21, 23162843828305

Offset: 2

Giovanni Resta, Aug 05 2018

No other terms below 4^60 ~= 1.3*10^36. The sequence is likely finite and complete. - Max Alekseyev, Aug 29 2023

			a(3) = A037301(3).
a(4) = A135122(2).
a(5) = A317777(2) = 23162843828305 in base 2, 3, 4, and 5 is equal to: 101010001000100000101000101000001000001010001, 10001000100100102010101011001, 11101010011011001001101, and 11014000001010001210, respectively. The sum of the digits is 13 in the 4 cases.

Cf. A037301, A135122, A317777.

isok(k, n) = #Set(vector(n-1, b, b++; sumdigits(k, b))) == 1;
a(n) = my(k=2); while (!isok(k, n), k++); k; \\ Michel Marcus, Sep 02 2023

a(2) = 2 prepended by Max Alekseyev, Aug 29 2023

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