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A062301 Number of ways writing n-th prime as a sum of two primes. 5
0, 0, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n)=1 if and only if n is in A006512. - Robert Israel, Apr 04 2018

LINKS

Muniru A Asiru, Table of n, a(n) for n = 1..3000

MATHEMATICA

Table[Sum[(PrimePi[Prime[n] - i] - PrimePi[Prime[n] - i - 1]) (PrimePi[i] - PrimePi[i - 1]), {i, Floor[Prime[n]/2]}], {n, 100}] (* Wesley Ivan Hurt, Apr 04 2018 *)

PROG

(PARI) a(n) = isprime(prime(n) - 2) \\ David A. Corneth, Apr 04 2018

(GAP) P:=Filtered([1..1000], IsPrime);; a:=List(List(List(P, i -> Partitions(i, 2)), k -> Filtered(k, i -> IsPrime(i[1]) and IsPrime(i[2]))), Length); # Muniru A Asiru, Apr 05 2018

CROSSREFS

Equals A061358(A000040(n)).

Cf. A006512, A014092, A025584.

Sequence in context: A284932 A117814 A257000 * A181712 A288729 A286807

Adjacent sequences:  A062298 A062299 A062300 * A062302 A062303 A062304

KEYWORD

nonn

AUTHOR

Labos Elemer, Jul 05 2001

EXTENSIONS

Offset changed to 1 by David A. Corneth, Apr 04 2018

STATUS

approved

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Last modified March 23 18:13 EDT 2019. Contains 321433 sequences. (Running on oeis4.)