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

1,1

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

Links

Table of n, a(n) for n=1..42.

Example

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

Mathematica

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

Crossrefs

Sequence in context: A135269 A234140 A362044 * A209378 A182466 A234133

Adjacent sequences: A086044 A086045 A086046 * A086048 A086049 A086050

Keyword

easy,nonn

Author

Shyam Sunder Gupta, Aug 24 2003

Status

approved