A386526 Products m of primorials (i.e., m in A025487) such that both m-1 and m+1 are not squarefree.

2097152, 13436928, 46656000, 1073741824, 1360800000, 12884901888, 1486016741376, 330225942528000, 358318080000000, 670777794086400, 1290482565120000, 64925062108545024, 69918208819200000, 137274424455168000, 164341563462254592, 277326388342554624, 415989582513831936

Offset: 1

Author

Michael De Vlieger, Jul 24 2025

Keywords

• nonn

Comments

Proper subset of A386527.

Examples

			Table of n, a(n), showing exponents of prime factors of a(n), and the prime decomposition of a(n)-1 and a(n)+1 for n = 1..6:
                 Exponents
n          a(n)  2.3.5.7  a(n)-1                    a(n)+1
-----------------------------------------------------------------------------
1      2097152  21        7^2, 127, 337             3^2, 43, 5419
2     13436928  11.8      7^2, 274223               11^2, 111049
3     46656000   9.6.3    13^2, 359, 769            7, 19^2, 37, 499
4   1073741824  30        3^2, 7, 11, 31, 151, 331  5^2, 13, 41, 61, 1321
5   1360800000   8.5.5.1  13^2, 107, 75253          11^2, 167, 67343
6  12884901888  32.1      11, 13^3, 563, 947        19^2, 35692249
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..164 (all terms less than A002110(21)).

Crossrefs

Cf. A000079, A002110, A013929, A025487, A375197, A386527.

Programs

Mathematica

(* Load function f from A025487, then: *)
Select[Union@ Flatten@ f[12], AllTrue[# + {-1, 1}, Not @* SquareFreeQ] &]