A080350 Costé prime expansion of 1/Pi.

5, 2, 7, 5, 3, 5, 11, 3, 7, 5, 2, 7, 79, 67, 19, 29, 59, 11, 5, 11, 3, 47, 31, 607, 419, 47, 19, 43, 37, 7, 3, 29, 7, 7, 5, 5, 157, 53, 89, 17, 5, 37, 7, 11, 3, 17, 5, 3, 3, 29, 127, 19, 11, 11, 5, 3, 13, 41, 13, 11, 3, 11, 11, 5, 11, 3, 3, 5, 2, 5, 2, 5, 3, 7, 3, 17, 5, 11, 3, 11, 17, 5, 3, 5

Offset

0,1

Comments

For x in (0,1], define P(x) = min{p: p prime, 1/x < p}, Phi(x) = P(x)x - 1. Costé prime expansion of x(0) is sequence a(0), a(1), ... given by x(n) = Phi(x(n-1)) (n>0), a(n) = P(x(n)) (n >= 0).

Links

Table of n, a(n) for n=0..83.

A. Costé, Sur un système fibré lié à la suite des nombres premiers, Exper. Math., 11 (2002), 383-405.

Maple

Digits := 500: P := proc(x) local y; y := ceil(evalf(1/x)); if isprime(y) then y else nextprime(y); fi; end; F := proc(x) local y, i, t1; y := x; t1 := []; for i from 1 to 100 do p := P(y); t1 := [op(t1), p]; y := p*y-1; od; t1; end; F(1/Pi);

Crossrefs

Cf. A079385, A079386, A079366, A079367, A079368, A080348, A080349.

Sequence in context: A084340 A065925 A250720 * A204899 A354827 A364521

Adjacent sequences: A080347 A080348 A080349 * A080351 A080352 A080353

Keyword

nonn,easy

Author

Mark Hudson (mrmarkhudson(AT)hotmail.com), Feb 17 2003

Status

approved