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A071177
Square-root of concatenation n'k, where k is minimal with n'k square (decimal notation).
2
4, 5, 6, 7, 23, 8, 27, 9, 31, 10, 34, 11, 37, 12, 39, 13, 42, 43, 14, 45, 46, 15, 152, 156, 16, 162, 165, 17, 54, 55, 56, 18, 58, 59, 188, 19, 61, 62, 63, 20, 203, 65, 66, 21, 213, 68, 69, 22, 222, 71, 72, 23, 73, 74, 235, 75, 24, 242
OFFSET
1,1
COMMENTS
a(n) = A000196(n'A071176(n))
EXAMPLE
a(5) = 23 as 23^2 = 529 = 5'29 and 5'i is nonsquare for i<29, A071176(5)=29.
PROG
(Python)
from math import isqrt
def A071177(n):
m = 10*n
if (k:=isqrt(m))**2!=m:
a = 1
while (k:=isqrt(a*(m+1)-1)+1)**2-m*a>=10*a:
a *= 10
return k # Chai Wah Wu, Feb 15 2023
CROSSREFS
Sequence in context: A161627 A030667 A030677 * A010754 A187807 A051036
KEYWORD
nonn,base
AUTHOR
Reinhard Zumkeller, May 15 2002
STATUS
approved