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A082462 Let chi(k) = 1 if prime(k+1) - prime(k) = 2, = 0 otherwise; sequence gives a(n) = sum_{k <= n} chi(k). 3
0, 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 8, 8, 8, 8, 8, 8, 9, 9, 10, 10, 10, 10, 10, 11, 11, 12, 12, 12, 12, 12, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 17, 17, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 20, 20, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..78.

FORMULA

a(n)=A071538(A000040(n)). [From R. J. Mathar, Oct 06 2008]

EXAMPLE

n p D a(n) (p=prime(n), D = prime(n+1)-prime(n))

1 2 1 0

2 3 2 1

3 5 2 2

4 7 4 2

5 11 2 3

6 13 4 3

CROSSREFS

Cf. A000040, A001223.

Sequence in context: A321578 A055086 A001462 * A276581 A005041 A030530

Adjacent sequences:  A082459 A082460 A082461 * A082463 A082464 A082465

KEYWORD

nonn

AUTHOR

Artemario Tadeu Medeiros da Silva (artemario(AT)uol.com.br), Apr 26 2003

STATUS

approved

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Last modified April 18 06:48 EDT 2019. Contains 322209 sequences. (Running on oeis4.)