login
A354342
Numbers divisible by a square greater than 1 that are the sum of two consecutive numbers divisible by a square greater than 1.
0
49, 99, 343, 351, 775, 847, 1025, 1449, 1665, 1681, 1849, 1863, 2057, 2151, 2367, 2575, 2825, 2889, 3175, 3185, 3249, 3609, 3625, 3699, 3725, 3751, 3871, 3951, 4113, 4375, 4599, 4625, 4913, 5047, 5049, 5193, 5239, 5391, 5751, 5887, 6137, 6175, 6425, 6713, 6849
OFFSET
1,1
COMMENTS
The sequence is infinite as it contains 29400*k + 49 for k >= 0. - David A. Corneth, Sep 12 2022
FORMULA
A008683(a(n)) = 0.
EXAMPLE
24 is divisible by 2 times 2, 25 by 5 times 5, and 24+25=49 divisible by 7 times 7. Next, 49 is divisible by 7 times 7, 50 is divisible by 5 times 5, the sum is 99 divisible by three times three.
MATHEMATICA
Select[2*Select[Range[5000], ! SquareFreeQ[#] && ! SquareFreeQ[# + 1] &] + 1, ! SquareFreeQ[#] &] (* Amiram Eldar, Sep 12 2022 *)
PROG
(PARI) is(n) = bitand(n, 1) && !issquarefree(n) && !issquarefree(n - n>>1) && !issquarefree(n >> 1) \\ David A. Corneth, Sep 12 2022
CROSSREFS
Subsequence of A013929 and A068781.
Sequence in context: A114013 A235578 A161689 * A230653 A019547 A228878
KEYWORD
nonn
AUTHOR
Daniel Barker, Sep 12 2022
EXTENSIONS
More terms from Amiram Eldar, Sep 12 2022
STATUS
approved