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A109578 a(n) = (pi(n+1)-pi(n)) * (prime(n+1)-prime(n)), where pi(k) is the number of prime numbers less than or equal to k (= A000720(k)) and prime(k) is the k-th prime number (= A000040(k)). 3
1, 2, 0, 4, 0, 4, 0, 0, 0, 2, 0, 4, 0, 0, 0, 6, 0, 6, 0, 0, 0, 4, 0, 0, 0, 0, 0, 2, 0, 14, 0, 0, 0, 0, 0, 6, 0, 0, 0, 6, 0, 10, 0, 0, 0, 12, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 6, 0, 2, 0, 0, 0, 0, 0, 14, 0, 0, 0, 4, 0, 8, 0, 0, 0, 0, 0, 4, 0, 0, 0, 10, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 6, 0, 0, 0, 6, 0, 6, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

FORMULA

a(n) = (A010051(1+n) * A001223(n)). - Antti Karttunen, Jan 03 2019

MAPLE

with(numtheory): a:=n->(pi(n+1)-pi(n))*(ithprime(n+1)-ithprime(n)): seq(a(n), n=1..160);

MATHEMATICA

an = Table[(PrimePi[n + 1] - PrimePi[n])*(Prime[n + 1] - Prime[n]), {n, 1, 200}]

PROG

(PARI) A109578(n) = ((primepi(n+1)-primepi(n)) * (prime(n+1)-prime(n))); \\ Antti Karttunen, Jan 03 2019

CROSSREFS

Cf. A001223, A010051.

Cf. also A096500, A096501.

Sequence in context: A119607 A279968 A164297 * A302826 A332903 A082519

Adjacent sequences:  A109575 A109576 A109577 * A109579 A109580 A109581

KEYWORD

nonn

AUTHOR

Roger L. Bagula, Jun 29 2005

STATUS

approved

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Last modified July 15 04:34 EDT 2020. Contains 335763 sequences. (Running on oeis4.)