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A275169 Positive integers not in the form x^3 + 2*y^2 + z^2 with x,y,z nonnegative integers. 3
15, 21, 47, 53, 79, 85, 92, 111, 117, 120, 181, 183, 245, 309, 311, 335, 372, 373, 398, 405, 421, 437, 447, 501, 565, 573, 629, 636, 645, 655, 693, 757, 791, 807, 820, 821, 853, 869, 885, 888, 949, 967, 1013, 1045, 1077, 1141, 1205, 1223, 1269, 1271, 1303, 1461, 1555, 1591, 1613, 1653, 2087, 2101, 2255, 2421 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Conjecture: The sequence has totally 174 terms as listed in the b-file the largest of which is 375565.

This implies the conjecture in A275150. We note that the sequence contains no term greater than 375565 and not exceeding 10^6.

See also A275168 for a similar conjecture.

LINKS

Zhi-Wei Sun, Table of n, a(n) for n = 1..174

EXAMPLE

a(1) = 15 since 15 is the least positive integer not in the form x^3 + 2*y^2 + z^2 with x,y,z nonnegative integers.

MATHEMATICA

SQ[n_]:=SQ[n]=IntegerQ[Sqrt[n]]

n=0; Do[Do[If[SQ[m-x^3-2*y^2], Goto[aa]], {x, 0, m^(1/3)}, {y, 0, Sqrt[(m-x^3)/2]}]; n=n+1; Print[n, " ", m]; Label[aa]; Continue, {m, 1, 2421}]

CROSSREFS

Cf. A000290, A000578, A022551, A022552, A262813, A270488, A274274, A275083, A275150, A275168.

Sequence in context: A247021 A129752 A015831 * A063176 A083372 A119101

Adjacent sequences:  A275166 A275167 A275168 * A275170 A275171 A275172

KEYWORD

nonn

AUTHOR

Zhi-Wei Sun, Jul 18 2016

STATUS

approved

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Last modified March 28 15:02 EDT 2020. Contains 333089 sequences. (Running on oeis4.)