A272910 Numbers n such that (n-1)^3 + (n+1)^3 is a taxi-cab number (A001235).

19, 32, 93, 124, 208, 243, 308, 395, 427, 471, 603, 672, 1057, 1568, 1892, 2181, 2223, 2587, 3040, 3049, 4037, 4336, 5232, 5556, 6196, 6305, 6643, 8288, 8748, 10161, 10185, 10612, 10985, 12352, 13741, 14807, 16021, 17568, 20352, 20653, 24080, 27216, 27867, 31113, 31869, 32032, 32500, 36593

Offset

1,1

Comments

Numbers n such that 2*n*(n^2+3) is a member of A001235.

19 and 3049 are the only prime numbers in this sequence for n < 10^5.

How is the graph of second differences of this sequence?

Links

Chai Wah Wu, Table of n, a(n) for n = 1..300

Example

19 is a term because 18^3 + 20^3 = 13832 = 2^3 + 24^3.

Prog

(PARI) T = thueinit(x^3+1, 1);
isA001235(n) = my(v=thue(T, n)); sum(i=1, #v, v[i][1]>=0 && v[i][2]>=v[i][1])>1;
lista(nn) = for(n=1, nn, if(isA001235(2*n*(n^2+3)), print1(n, ", ")));

Crossrefs

Cf. A001235, A153976, A259836.

Sequence in context: A184750 A101063 A061962 * A116168 A152088 A362410

Adjacent sequences: A272907 A272908 A272909 * A272911 A272912 A272913

Keyword

nonn

Author

Altug Alkan, May 09 2016

Status

approved