A034988 -id:A034988 - cp's OEIS frontend

A048351 a(n)^2 is the smallest square containing exactly n 6's.

4, 26, 216, 1291, 5164, 68313, 163284, 785294, 3559026, 26393686, 129099069, 254296413, 816435342, 4081257976, 80413106314, 215329205326, 2463064689907, 5165911014784, 24832773982716, 81401883640163, 752766125152206, 4086159158264236, 21602469586893686, 32659863237109026, 683788466294121304

Offset: 1

Patrick De Geest, Mar 15 1999

Eric Weisstein's World of Mathematics, Square Number

Cf. A036513, A034988.

a[n_] := Module[{i = 1}, While[DigitCount[i^2][[6]] != n, i++;]; i]; (* Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 20 2006 *)

def a(n):
  k = 1
  while not str(k**2).count('6') == n: k += 1
  return k
print([a(n) for n in range(1, 11)]) # Michael S. Branicky, Apr 26 2021

a(n) = sqrt(A036513(n)).

a(13) from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Aug 20 2006
a(14)-a(15) from Jon E. Schoenfield, Jan 14 2009
a(16) from Jon E. Schoenfield, Jan 24 2009
a(17)-a(20) from Giovanni Resta, Jul 27 2018
a(21)-a(25) from Max Alekseyev, Mar 06 2025

A034989 Smallest squares starting with a string of n 6's.

Original entry on oeis.org

64, 66049, 6661561, 6666724, 66666207204, 6666662032144, 66666669781156, 666666667972321, 666666666784689561, 66666666662139024481, 66666666666067063944516, 6666666666663510150195841, 66666666666662415539262729, 666666666666660853687280656

Offset: 1

Patrick De Geest, Nov 15 1998

Cf. A034988.

For[i = 1, i < 20, i++, zeros = 0; isFound = False;
While[ !isFound, low = Ceiling[ Sqrt[ 2/3*(10^i - 1)*10^zeros ] ]; high = Floor[ Sqrt[ (2/3*(10^i - 1) + 1)*10^zeros ] ]; isFound = (low <= high); zeros++ ]; Print[ low, " ", low^2 ] ]

Program and more terms from Jonathan Cross (jcross(AT)wcox.com), Oct 15 2001

cp's OEIS Frontend

A048351 a(n)^2 is the smallest square containing exactly n 6's.

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