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A113490 Semiprimes a such that there exist three semiprimes b, c and d with a^3=b^3+c^3+d^3. 0
206, 519, 703, 869, 1418, 1923, 1945, 2066, 2095, 2127, 2446, 2759, 2867, 2881, 2901, 2913, 2974, 3099, 3155, 3207, 3383, 3398, 3545, 3649, 3777, 3814, 3898, 4435, 4766, 4778, 4873, 4963, 5091, 5105, 5165, 5534, 5582, 5638, 5771, 5834, 5855, 6033, 6098 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

This is the semiprime analog of A114923.

There are only two such semiprimes < 10^4 with more than one solution: 2095 and 9897.

LINKS

Table of n, a(n) for n=1..43.

EXAMPLE

206^3 = 35^3 + 77^3 + 202^3.

519^3 = 4^3 + 303^3 + 482^3

703^3 = 111^3 + 291^3 + 685^3.

869^3 = 466^3 + 629^3 + 674^3.

2095^3 = 339^3 + 753^3 + 2059^3 = 543^3 + 1119^3 + 1969^3 (two ways).

9897^3 = 537^3 + 1454^3 + 9886^3 = 2071^3 + 3183^3 + 9755^3 (two ways).

Each of these numbers (other than the exponent 3) is a semiprime (A001358).

CROSSREFS

Cf. A001358, A114923.

Sequence in context: A252270 A113934 A260101 * A054007 A285754 A201032

Adjacent sequences:  A113487 A113488 A113489 * A113491 A113492 A113493

KEYWORD

nonn

AUTHOR

Jonathan Vos Post, Jan 09 2006

EXTENSIONS

Extended by Ray Chandler, Jan 20 2006

STATUS

approved

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Last modified October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)