login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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
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. also A096500, A096501.
Sequence in context: A164297 A349240 A366879 * A302826 A332903 A082519
KEYWORD
nonn
AUTHOR
Roger L. Bagula, Jun 29 2005
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 29 09:44 EDT 2024. Contains 371268 sequences. (Running on oeis4.)