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A238096 Sum_{k=2..n} floor(n/k)*floor((tau(k)+1)/2), where tau = A000005. 2
0, 1, 2, 5, 6, 10, 11, 16, 19, 23, 24, 33, 34, 38, 42, 50, 51, 60, 61, 70, 74, 78, 79, 94, 97, 101, 106, 115, 116, 129, 130, 141, 145, 149, 153, 172, 173, 177, 181, 196, 197, 210, 211, 220, 229, 233, 234, 257, 260, 269, 273, 282, 283, 298, 302, 317, 321, 325, 326, 353, 354, 358, 367, 382, 386, 399, 400, 409, 413, 426 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Number of quadratic polynomials with coefficients from {1..n} for which both roots are integers.

A generalization of A006318.

REFERENCES

D. Andrica and E. J. Ionascu, On the number of polynomials with coefficients in [n], An. St. Univ. Ovidius Constanta, 2013, to appear.

LINKS

Table of n, a(n) for n=1..70.

CROSSREFS

Cf. A000005, A006318, A238097, A238098.

Sequence in context: A179543 A077471 A273324 * A064572 A032399 A276496

Adjacent sequences:  A238093 A238094 A238095 * A238097 A238098 A238099

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Feb 22 2014

STATUS

approved

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Last modified July 27 18:27 EDT 2021. Contains 346308 sequences. (Running on oeis4.)