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A034980
a(n)^2 is smallest positive square starting with a string of n 2's.
3
1, 5, 15, 149, 4714, 47141, 471405, 1490712, 1490712, 471404521, 1490711985, 1490711985, 1490711985, 1490711985, 47140452079103, 149071198499986, 149071198499986, 14907119849998598, 14907119849998598, 471404520791031683, 14907119849998597976, 471404520791031682934, 4714045207910316829339
OFFSET
0,2
LINKS
EXAMPLE
a(5)^2 = 47141^2 = {22222}73881.
MAPLE
f:= proc(n) local x, k, s;
x:= 2*(10^n-1)/9;
for k from 0 do
s:= ceil(sqrt(10^k*x));
if s^2 < (x+1)*10^k then return s fi
od
end proc:
f(0):= 1:
map(f, [$0..30]); # Robert Israel, May 31 2023
CROSSREFS
Cf. A034981.
Sequence in context: A207971 A245648 A048347 * A174850 A143048 A261843
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Nov 15 1998
EXTENSIONS
More terms from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 23 2001
STATUS
approved