A290647 a(n) is the position of first occurrence of n^2 in the concatenation of the positive integers in decimal representation.

1, 4, 9, 22, 40, 62, 88, 83, 27, 190, 14, 322, 397, 478, 565, 658, 757, 37, 299, 1090, 323, 86, 777, 141, 660, 124, 783, 1325, 443, 2590, 479, 2986, 3246, 3514, 3790, 4074, 4366, 4666, 346, 5290, 394, 5946, 6286, 6634, 6990, 3541, 7261, 8106, 3851, 8890, 3931, 9706, 10126, 5408, 9012, 4345, 8865, 981, 4283, 13290, 4379

Offset

1,2

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Zhining Yang)

Example

s = 123456789101112131415161718192021222324252627282930313233343536... .
a(4) = 22 because the first occurrence of 4^2 = 16 in s starts at the 22nd digit.

Mathematica

t = ""; k = 0; Table[ While[(z = StringPosition[t, ToString[n^2], 1]) == {}, t = t <> ToString[++k]]; z[[1, 1]], {n, 61}] (* Giovanni Resta, Aug 11 2017 *)
Module[{nn=15000, s}, s=Flatten[IntegerDigits/@Range[nn]]; Flatten[Table[ SequencePosition[s, IntegerDigits[n^2], 1], {n, 70}], 1]][[All, 1]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 05 2021 *)

Prog

(VBA)
Sub test()
Dim i&, t$
For i = 1 To 10000
t = t & i
Next
For i = 1 To 100
Debug.Print InStr(t, i ^ 2); ", ";
Next
End Sub

Crossrefs

Cf. A031297, A290787.

Sequence in context: A041743 A041943 A158140 * A105314 A200155 A002835

Adjacent sequences: A290644 A290645 A290646 * A290648 A290649 A290650

Keyword

nonn,look,base

Author

Zhining Yang, Aug 08 2017

Status

approved