login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A138758 Index of A001203(n) (continued fraction for pi) in A000040 (primes), or 0 if A001203(n) is not prime. 3
2, 4, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0, 2, 6, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0, 2, 3, 0, 0, 0, 0, 0, 4, 0, 1, 2, 4, 0, 1, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 3, 1, 1, 2, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 2, 0, 1, 0, 0, 0, 1, 3, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..105.

FORMULA

a(n) = A000720(A001203(n)) * A010051(A001203(n))

EXAMPLE

This sequence starts 2,4,0,0,... since the first and 2nd terms of the continued fraction expansion of Pi, A001203 = (3, 7, 15, 1,...) are the 2nd resp. 4th primes, while the next two terms are not primes.

PROG

(PARI) default(realprecision, 1000); t=contfrac(Pi); vector(#t, i, isprime(t[i])*primepi(t[i]))

CROSSREFS

Cf. A001203, A138757, A138759, A005042.

Sequence in context: A166926 A266296 A028573 * A107501 A126732 A028586

Adjacent sequences:  A138755 A138756 A138757 * A138759 A138760 A138761

KEYWORD

nonn

AUTHOR

M. F. Hasler, Mar 31 2008

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 11 15:12 EDT 2020. Contains 336428 sequences. (Running on oeis4.)