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A056564 Number of times primes can be produced by taking the absolute difference between the n-th triangular number and another triangular number. 2
1, 1, 3, 2, 3, 2, 2, 3, 1, 1, 3, 1, 2, 2, 1, 1, 2, 2, 1, 3, 1, 1, 3, 1, 1, 1, 0, 1, 2, 2, 2, 2, 1, 0, 2, 1, 2, 2, 1, 0, 3, 1, 2, 2, 0, 1, 1, 2, 0, 2, 1, 1, 3, 2, 1, 2, 0, 1, 1, 1, 1, 1, 1, 0, 2, 0, 2, 2, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 0, 3, 1, 1, 1, 0, 1, 2, 2, 1, 1, 0, 0, 1, 1, 2, 3, 1, 1, 2, 1, 1, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..104.

FORMULA

a(n) =A056562(n)+A056563(n) =number of primes (with multiplicity) in {m, m+1, 2m-1, 2m+3}

EXAMPLE

a(2)=3 because 2nd triangular number is 3 and all three of 3-0=3, 3-1=2 and 6-3=3 are prime [n=2 is the only case where there is multiplicity].

CROSSREFS

Cf. A000217, A001227, A056562, A0565643

Sequence in context: A249355 A064654 A162229 * A082844 A101406 A245219

Adjacent sequences:  A056561 A056562 A056563 * A056565 A056566 A056567

KEYWORD

nonn

AUTHOR

Henry Bottomley, Jun 27 2000

STATUS

approved

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Last modified December 3 07:27 EST 2016. Contains 278698 sequences.