A086061 Sum of first n 8-almost primes.

256, 640, 1216, 1856, 2720, 3616, 4576, 5872, 7216, 8624, 10064, 11664, 13328, 15272, 17288, 19400, 21560, 23736, 25976, 28376, 30808, 33304, 36220, 39164, 42188, 45324, 48492, 51732, 54996, 58356, 61876, 65476, 69124, 72836, 76580

Offset

1,1

Comments

Elements in this sequence can themselves be 8-almost primes, as happens often for 5-almost primes. a(1) = 256 = 2^8. Also an 8-Brilliant number. a(2) = 640 = 2^7 * 5. Also an 8-Brilliant number. Does this happen infinitely often? - Jonathan Vos Post, Dec 11 2004

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

a(2)=640 because sum of first two 8-almost primes i.e. 256+384 is 640.

Mathematica

Accumulate[Select[Range[10000], Total[FactorInteger[#][[;; , 2]]]==8&]] (* Harvey P. Dale, Nov 02 2024 *)

Crossrefs

Sequence in context: A134609 A260065 A329488 * A235092 A237015 A237008

Adjacent sequences: A086058 A086059 A086060 * A086062 A086063 A086064

Keyword

easy,nonn

Author

Shyam Sunder Gupta, Aug 24 2003

Status

approved