A056564 - OEIS

A056564

Number of times primes can be produced by taking the absolute difference between the n-th triangular number and another triangular number.

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

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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, A056563

Sequence in context: A355034 A064654 A162229 * A082844 A279124 A101406

Adjacent sequences: A056561 A056562 A056563 * A056565 A056566 A056567

KEYWORD

nonn

AUTHOR

Henry Bottomley, Jun 27 2000

STATUS

approved