A139395 Decimal expansion of the sum 1/p(1) + 1/(p(2)*p(3)) + 1/(p(4)*p(5)*p(6)) + ..., where p(n) is the n-th prime.

5, 6, 7, 6, 7, 0, 3, 1, 9, 8, 4, 4, 5, 1, 9, 7, 2, 0, 8, 4, 0, 6, 9, 8, 2, 4, 2, 2, 9, 4, 2, 3, 2, 6, 7, 2, 5, 5, 8, 1, 1, 4, 8, 1, 3, 7, 3, 4, 6, 7, 3, 7, 8, 6, 3, 8, 3, 4, 2, 4, 9, 4, 7, 0, 5, 4, 8, 5, 8, 5, 1, 8, 7, 8, 5, 8, 7, 8, 4, 5, 9, 7, 3, 8, 2, 4, 3, 4, 1, 1, 9, 8, 1, 2, 1, 4, 3, 8, 3, 7

Offset: 0

Author

Paolo P. Lava and Giorgio Balzarotti, Apr 18 2008

Keywords

• nonn
• cons
• easy

Comments

Absolute difference between this number and A139396 is about 0.002.

Examples

			0.56767031984451972084069824229423267255811481373467378638342..
		

Crossrefs

Cf. A139396.

Programs

Maple

P:=proc(n) local a,b,i,j,k; a:=0.5; k:=1; for i from 2 by 1 to n do b:=1; for j from k by 1 to k+i-1 do b:=b*1/ithprime(j+1); od; k:=j; a:=evalf(a+b,105); od; print(a); end: P(100);

Mathematica

With[{nn=100},RealDigits[Total[1/Times@@@TakeList[Prime[Range[(nn(nn+1))/2]],Range[nn]]],10,120][[1]]] (* Harvey P. Dale, Dec 20 2024 *)