OFFSET
2,1
COMMENTS
17^(25/2) < a(17) <= 4159201115231103. - Martin Ehrenstein, Jul 10 2021
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
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