id:A136627 - OEIS Search Results

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For every number n in Ulam's spiral the sequence gives the number of primes around it (number n included).

+0
2

4, 3, 4, 3, 3, 3, 3, 3, 3, 2, 4, 5, 4, 2, 2, 2, 3, 3, 4, 3, 3, 2, 3, 2, 1, 0, 2, 3, 4, 3, 3, 2, 3, 1, 2, 2, 3, 3, 3, 2, 3, 3, 3, 1, 1, 2, 3, 2, 1, 1, 1, 1, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 2, 1, 3, 3, 3, 1, 2, 3, 5, 4, 4, 3, 2, 0, 1, 2, 2, 1, 1, 1, 1, 1, 2, 2, 2, 1, 2, 2, 1, 0, 2, 2, 4, 3, 3, 1, 0, 1, 1, 2 (list; graph; listen)

	OFFSET	`0,1`
	COMMENT	`In Ulam's lattice there are 8 numbers around any number. The sequence is similar to A136626 with an increment of 1 for any prime position.`
	EXAMPLE	`n=13: numbers around 13 are 3, 12, 29, 30, 31, 32, 33, 14 -> 3, 29, 31 and 13 itself are primes -> 4.`
	CROSSREFS	`Cf. A063826, A115258, A136626.` `Adjacent sequences: A136624 A136625 A136626 this_sequence A136628 A136629 A136630` `Sequence in context: A058290 A002285 A106049 this_sequence A108171 A106055 A103947`
	KEYWORD	`easy,nonn`
	AUTHOR	`Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Jan 14 2008`

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Last modified January 7 17:35 EST 2009. Contains 152824 sequences.

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