A324593 a(n) is the smallest number k such that n consecutive integers starting at k have the same number of odd divisors (A001227).

1, 1, 5, 10, 10, 515, 2314, 2314, 1536863, 4053992, 4053992, 18584686, 146237365, 163039279, 4775943486, 13147233734, 86153130379

Offset

1,3

Links

Table of n, a(n) for n=1..17.

Rémy Sigrist, C program for A324593

Example

515 has 4 odd divisors {1, 5, 103, 515}, 516 has 4 odd divisors {1, 3, 43, 129}, 517 has 4 odd divisors {1, 11, 47, 517}, 518 has 4 odd divisors {1, 7, 37, 259}, 519 has 4 odd divisors {1, 3, 173, 519} and 520 has 4 odd divisors {1, 5, 13, 65}. These the first 6 consecutive numbers with the same number of odd divisors, so a(6) = 515.

Prog

(C) See Links section.

Crossrefs

Cf. A001227, A006558, A045983, A045984, A323253, A324594.

Sequence in context: A256641 A032242 A208541 * A107975 A262665 A106792

Adjacent sequences: A324590 A324591 A324592 * A324594 A324595 A324596

Keyword

nonn,more

Author

Ilya Gutkovskiy, Sep 03 2019

Extensions

a(11)-a(14) from Rémy Sigrist, Sep 04 2019

a(15)-a(17) from Giovanni Resta, Sep 04 2019

Status

approved