A272889 - OEIS

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A272889

Cubefree taxi-cab numbers that are not squarefree.

40033, 443889, 1845649, 2048391, 4342914, 5799339, 26122131, 32973759, 41301953, 45882739, 53226297, 54269091, 65272753, 66763333, 70449093, 84637287, 86316741, 90527229, 91140435, 94100426, 104212017, 127396178, 128966383, 131126303, 131997229

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

There are two versions of "taxicab numbers" that are A001235 and A011541. This sequence focuses on the version A001235.

This sequence lists cubefree taxi-cab numbers that are divisible by a square greater than 1.

Intersection of A001235 and A067259.

Subsequence of A272885.

LINKS

Table of n, a(n) for n=1..25.

EXAMPLE

Taxi-cab number 40033 is a term because 40033 = 7^2*19*43.

Taxi-cab number 443889 is a term because 443889 = 3^2*31*37*43.

Taxi-cab number 1845649 is a term because 1845649 = 13^2*67*163.

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;

isA067259(n) = n>3 && vecmax(factor(n)[, 2])==2;

for(n=1, 1e10, if(isA001235(n) && isA067259(n), print1(n, ", ")));

CROSSREFS

Cf. A001235, A011541, A067259, A272885.

Sequence in context: A015328 A251970 A270261 * A126104 A031645 A250079

Adjacent sequences: A272886 A272887 A272888 * A272890 A272891 A272892

KEYWORD

nonn

AUTHOR

Altug Alkan, May 09 2016

STATUS

approved