A180109 a(1)=1 , thereafter, a(n) is the smallest integer k not yet in the sequence, such that k^2 contains in consecutive digits the decimal representation of a(n-1)

1, 4, 2, 5, 15, 34, 59, 77, 76, 24, 18, 43, 66, 108, 33, 58, 126, 355, 596, 186, 432, 208, 457, 214, 463, 681, 41, 21, 11, 46, 68, 83, 94, 97, 176, 42, 65, 81, 9, 3, 6, 8, 17, 131, 146, 121, 110, 105

Offset

1,2

Links

Jean-Marc Falcoz, Table of n, a(n) for n = 1..10000

Example

a(1)=1
a(2)=4, because 4^2=16 which contains 1
...
a(5)=15
a(6)=34, because 34^2=1156, which contains 15
a(7)=59, because 59^2=3481, which contains 34
...

Mathematica

but = 1500000; s = {1}; f[x_] := (sc = Complement[Range[but] , s]; n = ToString[x]; j = 1; While[StringPosition[ToString[sc[[j]]^2], n] == {}, j++]; sc[[j]]); a = 1; k = 1; While[a < 10001, k = f[k]; AppendTo[s, k]; a++]; Print[s]

Crossrefs

Sequence in context: A163358 A121709 A283747 * A019170 A107504 A141674

Adjacent sequences: A180106 A180107 A180108 * A180110 A180111 A180112

Keyword

base,nonn

Author

Jean-Marc Falcoz, Jan 16 2011

Status

approved