A283560 Concatenation of the first n nonsquares (A000037).
2, 23, 235, 2356, 23567, 235678, 23567810, 2356781011, 235678101112, 23567810111213, 2356781011121314, 235678101112131415, 23567810111213141517, 2356781011121314151718, 235678101112131415171819, 23567810111213141517181920
Offset: 1
Links
- Robert Israel, Table of n, a(n) for n = 1..365
- Eric Weisstein's World of Mathematics, Consecutive Number Sequences
Programs
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Maple
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: seq(A[n],n=1..20); # Robert Israel, Mar 13 2017
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Mathematica
cns[n_]:=FromDigits[Flatten[IntegerDigits[Table[k+Floor[1/2+Sqrt[k]],{k,1,n}]]]] Module[{nn=20,sqf},sqf=Select[Range[2,nn],!IntegerQ[Sqrt[#]]&];Table[FromDigits[Flatten[ IntegerDigits/@ Take[sqf,n]]],{n,Length[sqf]}]] (* Harvey P. Dale, Sep 07 2024 *) -
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
Comments