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Template:Sequence of the Day for June 29

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Intended for: June 29, 2012

Timetable

  • First draft entered by Alonso del Arte on March 28, 2011. ✓
  • Draft reviewed by Daniel Forgues on April 21, 2011. ✓
  • Draft approved by T. D. Noe on May 23, 2011.✓
Yesterday's SOTD * Tomorrow's SOTD

The line below marks the end of the <noinclude> ... </noinclude> section.



A090684: Primes of the form
8 n 2  −  1
.
{ 7, 31, 71, 127, 199, 647, 967, 1151, 1567, 2311, 2591, 2887, 3527, 4231, ... }
221 223 225 227 229 231 233 235 237 239 241
219 145 147 149 151 153 155 157 159 161 163
217 143 85 87 89 91 93 95 97 99 165
215 141 83 41 43 45 47 49 51 101 167
213 139 81 39 13 15 17 19 53 103 169
211 137 79 37 11 1 3 21 55 105 171
209 135 77 35 9 7 5 23 57 107 173
207 133 75 33 31 29 27 25 59 109 175
205 131 73 71 69 67 65 63 61 111 177
203 129 127 125 123 121 119 117 115 113 179
201 199 197 195 193 191 189 187 185 183 181

In the odd number variant of the Ulam spiral, unencumbered by the even numbers, the prime numbers can line up in horizontal and vertical lines. But there are still noticeable diagonal lines of primes, and these primes fall on one such diagonal.