Template:Sequence of the Day for April 24

Intended for: April 24, 2013

Timetable

• First draft entered by Alonso del Arte on March 19, 2012 ✓
• Draft reviewed by Daniel Forgues on April 26, 2012 ✓
• Draft approved by Alonso del Arte on January 12, 2013 ✓

Yesterday's SOTD * Tomorrow's SOTD

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A187677: Primes of the form

8 n 2 + 6 n  −  1

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221	223	225	227	229	231	233	235
219	145	147	149	151	153	155	157
217	143	85	87	89	91	93	95
215	141	83	41	43	45	47	49
213	139	81	39	13	15	17	19
211	137	79	37	11	1	3	21
209	135	77	35	9	7	5	23

In a variant of the Ulam spiral in which only odd numbers are entered, some primes still line up along some diagonals but not others. Without the even numbers, primes can also line up in horizontal and diagonal lines. This sequence comes from an upwards vertical line which starts with 13.