A139516 Denominators of an Egyptian fraction for "e", using only prime numbers and allowing repetitions.

2, 2, 2, 2, 2, 5, 59, 751, 894503, 18292510297, 5993565343364843081, 818638308229506590060391447618925613, 5089762493052274984454740075748133007549187136115352857668628331136557

Offset

0,1

Links

Table of n, a(n) for n=0..12.

Example

1/2+1/2+1/2+1/2 = 2 (integer part of "e").
1/2+1/5+1/59+1/751 gives an approximation that is good to 10 decimal digits.
Adding the other fractions we get approximations good to 18, 35, 69, 137, 272, 541 decimal digits.

Maple

P:=proc(n) local a, i; a:=evalf(exp(1)-2, 100); for i from 1 by 1 to 4 do print(2); od; for i from 1 by 1 to n do if 1/ithprime(i)<a then a:=a-1/ithprime(i); print(a); print(ithprime(i)); fi; od; end: P(100000);

Crossrefs

Cf. A139514, A139515, A139517-A139523.

Sequence in context: A172414 A266995 A051887 * A225953 A278247 A160762

Adjacent sequences: A139513 A139514 A139515 * A139517 A139518 A139519

Keyword

easy,nonn

Author

Paolo P. Lava and Giorgio Balzarotti, Apr 24 2008

Status

approved