Michael P. Tilley - cp's OEIS frontend

User: Michael P. Tilley

Michael P. Tilley has authored 2 sequences.

A268068 First occurrence of n in the decimal expansion of Mersenne prime 2^74207281 - 1.

2, 8, 18, 1, 7, 20, 6, 5, 9, 22, 167, 240, 196, 156, 51, 143, 31, 241, 8, 74, 18, 73, 138, 71, 154, 217, 96, 119, 160, 21, 1, 166, 72, 63, 64, 28, 87, 4, 172, 57, 210, 7, 81, 56, 103, 65, 12, 68, 52, 374, 35, 239, 20, 90, 67, 66, 38, 178, 42, 29, 13, 15, 174, 44, 6

Offset: 0

Michael P. Tilley, Jan 25 2016

The largest known prime as of Jan 07 2016 is 2^74207281 - 1. The number itself contains 22,338,618 digits; all integers with fewer than 7 digits are contained within M74207281. The first number not contained in M74207281 is 1000003, so this sequence stops at a(1000002) = 1505496.

			The first few digits of M74207281 are 30037641808460618205298609835916605...
Starting with three as the first digit count the position of n from the beginning
  0 is the second digit,
  1 is the eighth digit,
  2 18,
  3 1,
  4 7,
  etc.

Michael P. Tilley, Table of n, a(n) for n = 0..9999
Brady Haran and Matt Parker, More details about the World's Biggest Prime (2016).
Michael P. Tilley, A larger file of the sequence for n= 0 - 1000002

Cf. A000043, A267875.

With[{m = IntegerDigits[2^74207281 - 1]}, Array[SequencePosition[m, IntegerDigits[#], 1][[1, 1]] &, 100, 0]] (* Paolo Xausa, Apr 07 2024 *)

A248715 Isolated numbers: Mark the lowest number that doesn't touch a number that has already been mark on grid of number spiraling outward.

Original entry on oeis.org

1, 10, 12, 15, 17, 19, 21, 23, 31, 48, 50, 52, 54, 60, 62, 64, 67, 69, 71, 73, 75, 77, 89, 91, 93, 101, 118, 120, 122, 124, 126, 128, 138, 140, 142, 148, 150, 152, 154, 156, 159, 161, 163, 179, 181, 183, 185, 187, 195, 197, 199, 211, 220, 222, 224, 226, 228

Offset: 1

Michael P. Tilley, Oct 12 2014

nonn

Start by creating a grid of integers starting with 1 in the center and spiraling outward.
.
  64--63--62--61--60--59--58--57
                               |
  37--36--35--34--33--32--31  56
   |                       |   |
  38  17--16--15--14--13  30  55
   |   |               |   |   |
  39  18   5---4---3  12  29  54
   |   |   |       |   |   |   |
  40  19   6   1---2  11  28  53
   |   |   |           |   |   |
  41  20   7---8---9--10  27  52
   |   |                   |   |
  42  21--22--23--24--25--26  51
   |                           |
  43--44--45--46--47--48--49--50
.
Then starting with 1 mark all numbers that have no neighboring marked numbers.
.
. 64    62    60      
.
.             31  
.
.   17    15        
.
.           12    54
.
.   19     1        
.
.           10    52
.
.   21    23        
.
.           48    50

Michael P. Tilley, Table of n, a(n) for n = 1..10383
Michael P. Tilley, Image of a 204 X 204 grid

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User: Michael P. Tilley

A268068 First occurrence of n in the decimal expansion of Mersenne prime 2^74207281 - 1.

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