A067478 -id:A067478 - cp's OEIS frontend

A067479 Smallest n-digit square starting with 9, or 0 if no such number exists.

9, 0, 900, 9025, 90000, 900601, 9000000, 90003169, 900000000, 9000127161, 90000000000, 900001331856, 9000000000000, 90000000369889, 900000000000000, 9000000036988900, 90000000000000000, 900000001801523401

Offset: 1

Amarnath Murthy, Feb 09 2002

Cf. A000290, A035076 (roots), A045792.

Cf. 2: A067472, 3: A067473, 4: A067474, 5: A067475, 6: A067476, 7: A067477, 8: A067478.

a(n) = if (n==2, 0, (sqrtint(9*10^(n-1)) + (n-1) % 2)^2); \\ Michel Marcus, Mar 23 2021

a(n+1) = (floor(sqrt(9*10^n)) + (n mod 2))^2, a(2)=0. - Sascha Kurz, Mar 18 2002

a(2k+1) = 9 * 10^(2k) for k >= 0. - Bernard Schott, Mar 23 2021

More terms from Sascha Kurz, Mar 18 2002

A035075 a(n) = ceiling(sqrt(8*10^n)).

Original entry on oeis.org

9, 29, 90, 283, 895, 2829, 8945, 28285, 89443, 282843, 894428, 2828428, 8944272, 28284272, 89442720, 282842713, 894427191, 2828427125, 8944271910, 28284271248, 89442719100, 282842712475, 894427191000, 2828427124747

Offset: 1

Patrick De Geest, Nov 15 1998

Also, first term of runs of consecutive numbers whose square starts with the digit 8.

Cf. A067478 (squares), A035069-A035076 (2..9), A045862.

Ceiling[Sqrt[8*10^Range[30]]] (* Harvey P. Dale, Apr 12 2013 *)

from math import isqrt
def a(n): return isqrt(8*10**n) + 1
print([a(n) for n in range(1, 25)]) # Michael S. Branicky, Sep 29 2021

a(n) = ceiling(sqrt(8*10^n)), n > 0.

cp's OEIS Frontend

A067479 Smallest n-digit square starting with 9, or 0 if no such number exists.

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