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A069292
Sum of square roots of square divisors of n <= sqrt(n).
3
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 1, 1, 1, 3, 4, 1, 1, 3, 1, 1, 1, 3, 1, 4, 1, 3, 1, 1, 1, 3, 1, 1, 4, 3, 1, 1, 1, 3, 1
OFFSET
1,16
FORMULA
G.f.: Sum_{k>=1} k * x^(k^4) / (1 - x^(k^2)). - Ilya Gutkovskiy, Aug 19 2021
MATHEMATICA
Table[DivisorSum[n, Sqrt@ # &, And[IntegerQ@ Sqrt@ #, # <= Sqrt@ n] &], {n, 105}] (* Michael De Vlieger, Nov 20 2017 *)
PROG
(PARI) A069292(n) = { my(r="NA"); sumdiv(n, d, (issquare(d, &r)&&((d^2)<=n))*r); } \\ Antti Karttunen, Nov 20 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Mar 14 2002
EXTENSIONS
More terms from Antti Karttunen, Nov 20 2017
STATUS
approved