A290787 a(n) is the position of the first occurrence of n^3 in the concatenation of the positive integers in decimal representation.

1, 8, 44, 83, 265, 378, 58, 267, 783, 2890, 289, 5802, 6781, 9866, 12390, 15274, 4288, 9223, 22764, 30890, 6595, 42130, 49725, 58010, 1575, 76770, 87305, 7670, 110835, 123890, 53786, 127309, 168575, 11048, 10389, 1884, 164216, 116326, 86857, 188924, 73351, 15241, 30690, 81318, 45139, 157378, 511828, 41849, 594784, 638890

Offset

1,2

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000 (terms 1..100 from Zhining Yang)

Example

3^3 = 27, so a(3) = 44 because the digit string "27" first occurs beginning at the 44th digit of the string
  s = "12345678910111213141516171819202122232425262728...":
.
.                  1         2         3         4
Position: 12345678901234567890123456789012345678901234567...
                                                     vv
       s: 12345678910111213141516171819202122232425262728...
                                                     ^^

Mathematica

T = StringJoin @@ ToString /@ Range@ 700000; Table[StringPosition[T, ToString[ n^3], 1][[1, 1]], {n, 50}] (* Giovanni Resta, Aug 11 2017 *)

Prog

(VBA)
Sub test()
Dim i&, t$, s$(1 To 125000)
For i = 1 To 125000
s(i) = i
Next
t = Join(s, "")
For i = 1 To 50
Debug.Print InStr(t, i ^ 3); ", ";
Next
End Sub

Crossrefs

Cf. A031297, A290647.

Sequence in context: A046329 A046377 A075816 * A188148 A316466 A100583

Adjacent sequences: A290784 A290785 A290786 * A290788 A290789 A290790

Keyword

nonn,look,base

Author

Zhining Yang, Aug 10 2017

Status

approved