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A098726 Take three consecutive primes started with the n-th prime:{p(n),p(n+1),p(n+2)}. Calculate d(i,j)=Abs[p(i)-p(j)], for all {i,j}, i.e. all possible differences. a[n] is the number of distinct differences which are either 3 or 2. +0
2
3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3 (list; graph; listen)
OFFSET

1,1

EXAMPLE

a[n]=2 iff the consecutive prime-differences are equal.

MATHEMATICA

k=3; t=Table[Abs[Prime[n+i]-Prime[n+j]], {i, 0, k-1}, {j, 0, k-1}]; u=Delete[Union[Flatten[t]], 1]; a(n)=Length[u]

CROSSREFS

Cf. A080370, A054643.

Sequence in context: A080428 A120004 A079790 this_sequence A065801 A086920 A117451

Adjacent sequences: A098723 A098724 A098725 this_sequence A098727 A098728 A098729

KEYWORD

nonn

AUTHOR

Labos E. (labos(AT)ana.sote.hu), Oct 05 2004

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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