A086047 Sum of first n 5-almost primes.

32, 80, 152, 232, 340, 452, 572, 734, 902, 1078, 1258, 1458, 1666, 1909, 2161, 2425, 2695, 2967, 3247, 3547, 3851, 4163, 4531, 4909, 5301, 5697, 6102, 6510, 6930, 7370, 7820, 8276, 8740, 9208, 9704, 10204, 10724, 11276, 11843, 12431, 13023, 13617

Offset: 1

Author

Shyam Sunder Gupta, Aug 24 2003

Keywords

• easy
• nonn

Comments

Elements in this sequence can themselves be 5-almost primes. a(1) = 32 = 2^5. a(2) = 80 = 2^4 * 5. a(27) = 6102 = 2 * 3^3 * 113 a(28) = 6510 = 2 * 3 * 5 * 7 * 31 a(31) = 7820 = 2^2 * 5 * 17 * 23 a(33) = 8740 = 2^2 * 5 * 19 * 23. Does this happen infinitely often? - Jonathan Vos Post, Dec 11 2004

Examples

			a(2)=80 because sum of first two 5-almost primes, i.e. 32+48, is 80.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Partial sums of A014614.

Programs

Mathematica

Accumulate[Select[Range[1000],PrimeOmega[#]==5&]] (* Harvey P. Dale, Jan 19 2018 *)