A271817 Smallest k > 1 such that none of k^2 + 0, k^2 + 1, k^2 + 2,..., k^2 + n are squarefree.

2, 7, 32, 41, 239, 13982, 240761, 240761, 26220368, 93499279

Offset

0,1

Comments

a(10) > 1.2*10^8. - Giovanni Resta, Apr 15 2016

Links

Table of n, a(n) for n=0..9.

Example

a(0) = 2 because 2 > 1 and none of 2^2 + 0 = 4 = 2^2 is squarefree,
a(1) = 7 because none of 7^2 + 0 = 49 = (7^2), 7^2 + 1 = 50 =(5^2)*2 are squarefree,
a(2) = 32 because none of 32^2 + 0 = 1024 = (2^2)*156, 32^2 + 1 = 1025 = (5^2)*41, 32^2 + 2 = 1026 = (3^2)*114 are squarefree.

Prog

(PARI) isok(k, n) = {for (j=0, n, if (issquarefree(k^2+j), return (0)); ); 1; }
a(n) = {my(k = 2); while (! isok(k, n), k++); k; } \\ Michel Marcus, Apr 14 2016

Crossrefs

Cf. A013929, A045882, A270442.

Sequence in context: A355541 A158940 A102161 * A015655 A320682 A344130

Adjacent sequences: A271814 A271815 A271816 * A271818 A271819 A271820

Keyword

nonn,more

Author

Juri-Stepan Gerasimov, Apr 14 2016

Extensions

a(8)-a(9) from Giovanni Resta, Apr 15 2016

Status

approved