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A109444
Cumulative sum of mosaic numbers (A000026).
0
1, 3, 6, 10, 15, 21, 28, 34, 40, 50, 61, 73, 86, 100, 115, 123, 140, 152, 171, 191, 212, 234, 257, 275, 285, 311, 320, 348, 377, 407, 438, 448, 481, 515, 550, 574, 611, 649, 688, 718, 759, 801, 844, 888, 918, 964, 1011, 1035, 1049, 1069, 1120, 1172, 1225
OFFSET
1,2
COMMENTS
Integers in this sequence which are themselves primes include a(2) = 3, a(11) = 61, a(12) = 73, a(20) = 191, a(23) = 257, a(26) = 311, a(62) = 1697, a(67) = 1949, a(68) = 2017. Integers in this sequence which are perfect powers greater than 1 of composites include a(14) = 100, a(53) = 1225.
FORMULA
A000026(Product (p_j^k_j)) = Product (p_j * k_j).
a(n) = Sum_{i=1..n} A000026(i).
MATHEMATICA
Accumulate[Array[Times@@Flatten[FactorInteger[#]]&, 60]] (* Harvey P. Dale, Sep 16 2018 *)
CROSSREFS
Cf. A000026.
Sequence in context: A231680 A124158 A161208 * A124157 A033440 A067525
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Aug 26 2005
STATUS
approved