A071177 Square-root of concatenation n'k, where k is minimal with n'k square (decimal notation).

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))

Links

Table of n, a(n) for n=1..58.

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

Adjacent sequences: A071174 A071175 A071176 * A071178 A071179 A071180

Keyword

nonn,base

Author

Reinhard Zumkeller, May 15 2002

Status

approved