A335830 Decimal expansion of the sum of the reciprocals of the multiply-perfect numbers.

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

Offset: 1

Author

Amiram Eldar, Jun 25 2020

Keywords

• nonn
• cons

Comments

The first 18 terms were calculated by Bayless and Kinlaw (2015).

Examples

			1.21440760859142719...
		

Links

• Jonathan Bayless and Paul Kinlaw, On repeated values of sigma and multiperfect numbers, Journal of Combinatorics and Number Theory, Vol. 7, No. 3 (2015), pp. 177-189.

Crossrefs

Cf. A007691, A335118.

Programs

Mathematica

multiPerfects = Cases[Import["https://oeis.org/A007691/b007691.txt", "Table"], {, }][[;; , 2]]; RealDigits[Total[1/multiPerfects], 10, 18][[1]]

Formula

Equals Sum_{k>=1} 1/A007691(k).

Extensions

More terms (computed using the b-file at A007691) from Jon E. Schoenfield, Jan 25 2021