A076872 a(n) = number of numbers <= n that are the sum of two squarefull numbers.

0, 1, 1, 1, 2, 2, 2, 3, 4, 5, 5, 6, 7, 7, 7, 8, 9, 10, 10, 11, 11, 11, 11, 12, 13, 14, 14, 15, 16, 16, 17, 18, 19, 20, 21, 22, 23, 23, 23, 24, 25, 25, 26, 27, 28, 28, 28, 29, 29, 30, 30, 31, 32, 33, 33, 33, 34, 35, 36, 36, 37, 37, 38, 39, 40, 40, 40, 41, 41, 41, 41, 42, 43, 44, 44

Offset

1,5

References

Aleksandar Ivić, The Riemann Zeta-Function, Wiley, NY, 1985, see p. 439.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

With[{m = 120}, pow = Select[Range[m], # == 1 || Min[FactorInteger[#][[;; , 2]]] > 1 &]; Accumulate @ BinCounts[Select[Union[Plus @@@ Tuples[pow, {2}]], # <= m &], {1, m, 1}]] (* Amiram Eldar, Feb 12 2023 *)

Crossrefs

Cf. A001694, A076871.

Sequence in context: A230413 A029096 A194820 * A008906 A029074 A258741

Adjacent sequences: A076869 A076870 A076871 * A076873 A076874 A076875

Keyword

nonn,easy

Author

N. J. A. Sloane, Nov 25 2002

Extensions

More terms from Vladeta Jovovic, Nov 26 2002

Status

approved