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

Author

Shyam Sunder Gupta, Aug 24 2003

Keywords

• easy
• nonn

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

Examples

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

Links

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

Programs

Mathematica

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