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A048351
a(n)^2 is the smallest square containing exactly n 6's.
2
4, 26, 216, 1291, 5164, 68313, 163284, 785294, 3559026, 26393686, 129099069, 254296413, 816435342, 4081257976, 80413106314, 215329205326, 2463064689907, 5165911014784, 24832773982716, 81401883640163
OFFSET
1,1
COMMENTS
a(21) > 10^14. - Giovanni Resta, Jul 27 2018
LINKS
Eric Weisstein's World of Mathematics, Square Number
FORMULA
a(n) = sqrt(A036513(n)).
MATHEMATICA
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 *)
PROG
(Python)
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
CROSSREFS
Sequence in context: A283828 A306028 A164101 * A224734 A143436 A135884
KEYWORD
nonn,base,more
AUTHOR
Patrick De Geest, Mar 15 1999
EXTENSIONS
816435342 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
STATUS
approved