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A249896
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a(n+1) is next smallest square not divisible by 10 beginning with a(n), initial term is 6.
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5
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6, 64, 64009, 6400960036, 640096003602877347904, 640096003602877347904912233550482787380625, 6400960036028773479049122335504827873806251020537411455326101704116338781035920283225
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OFFSET
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1,1
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COMMENTS
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a(11) has 1374 digits, a(12) has 2749, a(13) has 5499, a(14) has 10998. - Robert Israel, Nov 25 2020
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LINKS
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MAPLE
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R:= 6: x:= 6: s:= 2:
for iter from 1 while length(x) < 1000 do
for d from 1 do
if d::even then sp:= 1+ 10^(d/2)*s
else
sp:= ceil(sqrt(10^d*x));
if sp mod 10 = 0 then sp:=sp+1; fi
fi;
if sp^2 < (x+1)*10^d then
x:= sp^2; s:= sp; R:= R, x; break
fi
od;
od:
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PROG
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(PARI) a(n)=k=n; s=1; while(s<5*10^7, if(s%10, if(s^2\(10^(#Str(s^2)-#Str(k)))==k, print1(s^2, ", "); k=s^2)); s++)
a(7)
(Python)
def f(x):
..print(x, end=', ')
..n = x
..s = 1
..while s < 10**7:
....if s % 10:
......S = str(s**2)
......if S.startswith(str(n)):
........print(s**2, end=', ')
........n = s**2
....s += 1
f(7)
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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