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A085323
Numbers k such that both k and k+1 are sums of two positive cubes.
4
854, 4940, 9603, 10744, 17919, 29743, 62558, 79001, 133273, 164304, 193192, 205406, 214984, 242648, 263871, 378936, 431999, 447336, 488375, 517427, 610687, 731158, 762047, 1000511, 1061550, 1125207, 1134124, 1157632, 1158137, 1179520
OFFSET
1,1
COMMENTS
There are 664 terms < 8*10^9, a(664)=7999968373. - Zak Seidov, Jul 24 2009
This is an infinite sequence. To see why, consider the (N,N+1) pair N = 16*k^6 - 12*k^4 + 6*k^2 - 2 = (2*k^2 - k - 1)^3 + (2*k^2 + k -1)^3 and N + 1 = 16*k^6 - 12*k^4 + 6*k^2 - 1 = (2*k^2)^3 + (2*k^2 - 1)^3. - Ant King, Sep 20 2013
EXAMPLE
854 = 9^3 + 5^3 and 855 = 8^3 + 7^3;
4940 = 17^3 + 3^3 and 4941 = 13^3 + 14^3.
MATHEMATICA
{m=100, k=3, m^k}; t=Union[Flatten[Table[Table[w^k+q^k, {w, 1, m}], {q, 1, m}]]]; dt=Delete[ -RotateRight[t]+t, 1]; p=Part[t, Flatten[Position[dt, 1]]]; p
CROSSREFS
Cf. A003325.
Sequence in context: A127593 A248856 A251050 * A185639 A105275 A100969
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 01 2003
EXTENSIONS
Corrected and extended by Zak Seidov, Jul 24 2009
Name and Example edited by Jon E. Schoenfield, Jul 29 2017
STATUS
approved