id:A090970 - OEIS Search Results

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Number of primes strictly between T(n) and T(n+1), where T(n) = n-th triangular number.

+0
3

1, 1, 1, 2, 2, 1, 2, 3, 2, 2, 3, 3, 3, 3, 2, 4, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 6, 4, 5, 3, 6, 6, 7, 5, 5, 6, 4, 8, 5, 6, 6, 8, 6, 8, 5, 7, 5, 11, 4, 6, 9, 7, 8, 9, 8, 7, 7, 9, 7, 8, 7, 12, 5, 9, 9, 11, 9, 7, 7, 12, 10, 10, 9, 9, 9, 6, 11, 10, 11, 9, 12, 11, 12, 9, 10, 11, 12, 10, 13, 9, 11, 10, 12 (list; graph; listen)

	OFFSET	`1,4`
	LINKS	`T. D. Noe, Table of n, a(n) for n=1..1000`
	EXAMPLE	`a(8)=3 because between T(8)=36 and T(9)=45 we have the prime numbers 37,41, and 43.`
	MAPLE	`a:=proc(n) local ct, j: ct:=0: for j from n(n+1)/2+1 to (n+1)(n+2)/2-1 do if isprime(j)=true then ct:=ct+1 else ct:=ct fi: od: end: seq(a(n), n=1..103); (Deutsch)`
	CROSSREFS	`Essentially the same as A065382 and A066888.` `Sequence in context: A056173 A027348 A023566 this_sequence A091972 A025833 A035462` `Adjacent sequences: A090967 A090968 A090969 this_sequence A090971 A090972 A090973`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jan 03 2004`
	EXTENSIONS	`More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 23 2005`

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Last modified August 19 23:53 EDT 2008. Contains 142930 sequences.

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