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URL: https://oeis.org/A387616

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A387616
Numbers k that are less than distance j from j! for some positive integer j.
0
1, 2, 3, 4, 5, 6, 7, 8, 21, 22, 23, 24, 25, 26, 27, 116, 117, 118, 119, 120, 121, 122, 123, 124, 715, 716, 717, 718, 719, 720, 721, 722, 723, 724, 725, 5034, 5035, 5036, 5037, 5038, 5039, 5040, 5041, 5042, 5043, 5044, 5045, 5046, 40313, 40314
OFFSET
1,2
EXAMPLE
Seen as an irregular triangle:
1, 2, 3; (between 2!-1 and 2!+1)
4, 5, 6, 7, 8; (between 3!-2 and 3!+2)
21, 22, 23, 24, 25, 26, 27, ...;
116, 117, 118, 119, 120, 121, 122, 123, 124, ....
MATHEMATICA
a[n_] := Module[{m = Floor[Sqrt[n]]}, (m+1)! + n - m^2 - m]; Array[a, 50] (* Amiram Eldar, Sep 04 2025 *)
CROSSREFS
Cf. A000142.
Sequence in context: A366947 A366838 A236836 * A371260 A215888 A240963
KEYWORD
nonn,easy
AUTHOR
Dwight Boddorf, Sep 03 2025
STATUS
approved