id:A074787 - OEIS Search Results

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Sum of squares of the number of unitary divisors of k from 1 to n.

+0
2

1, 5, 9, 13, 17, 33, 37, 41, 45, 61, 65, 81, 85, 101, 117, 121, 125, 141, 145, 161, 177, 193, 197, 213, 217, 233, 237, 253, 257, 321, 325, 329, 345, 361, 377, 393, 397, 413, 429, 445, 449, 513, 517, 533, 549, 565, 569, 585, 589, 605, 621, 637, 641, 657, 673 (list; graph; listen)

	OFFSET	`1,2`
	FORMULA	`a(n)= Sum_{k=1..n} ud(k)^2 = Sum_{k=1..n} A034444(k)^2 . a(n) = Sum_{k=1..n} 2^(2omega(k)) = Sum_{k=1..n} 2^(2A001221(k)).`
	MAPLE	`with(numtheory): seq(add(2^(2*nops(ifactors(k)[2])), k=1..n), n=1..100);`
	CROSSREFS	`Cf. A034444, A064608.` `Equals 4*A069811(n) + 1.` `Sequence in context: A085759 A032493 A125018 this_sequence A079497 A081835 A088907` `Adjacent sequences: A074784 A074785 A074786 this_sequence A074788 A074789 A074790`
	KEYWORD	`nonn`
	AUTHOR	`Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Sep 07 2002`

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Last modified December 10 00:48 EST 2009. Contains 170565 sequences.

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