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A283560
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Concatenation of the first n nonsquares (A000037).
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2
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2, 23, 235, 2356, 23567, 235678, 23567810, 2356781011, 235678101112, 23567810111213, 2356781011121314, 235678101112131415, 23567810111213141517, 2356781011121314151718, 235678101112131415171819, 23567810111213141517181920
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OFFSET
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1,1
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COMMENTS
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There are 5 primes in the first 6100 terms of this sequence, see A283561.
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LINKS
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MAPLE
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A[1]:= 2:
x:= 2:
for n from 2 to 20 do
if issqr(x+1) then x:= x+2 else x:= x+1 fi;
A[n]:= A[n-1]*10^(1+ilog10(x))+x;
od:
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MATHEMATICA
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cns[n_]:=FromDigits[Flatten[IntegerDigits[Table[k+Floor[1/2+Sqrt[k]], {k, 1, n}]]]]
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PROG
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(PARI) a(n)=my(s=""); for(k=1, n, s=Str(s, (sqrtint(4*k)+1)\2 + k)); eval(s) \\ Charles R Greathouse IV, Mar 10 2017
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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