A369182 Numbers k such that d(k) is greater than d(k-2), d(k-1), d(k+1) and d(k+2) where d(k) is the number of divisors of k.

12, 24, 30, 36, 48, 60, 66, 72, 80, 84, 90, 96, 100, 108, 112, 120, 126, 132, 140, 144, 150, 156, 160, 165, 168, 176, 180, 192, 204, 210, 216, 220, 224, 228, 234, 240, 252, 256, 260, 264, 270, 276, 280, 288, 294, 300, 312, 315, 320, 324, 330, 336, 357, 360, 364, 368, 372

Offset

1,1

Links

Table of n, a(n) for n=1..57.

Example

30 is a term since d(28) = 6, d(29) = 2, d(30) = 8, d(31) = 2, d(32) = 6 and 6 < 8 > 6, 2 < 8 > 2.

Maple

q:= n-> (t-> t(n)>max(map(t, {n-2, n-1, n+1, n+2})))(numtheory[tau]):
select(q, [$3..372])[];  # Alois P. Heinz, Apr 12 2026

Mathematica

SequencePosition[Table[DivisorSigma[0, n], {n, 1, 400}], {a_, b_, c_, d_, e_} /; Max[a, b, d, e] < c][[;; , 1]] + 2 (* Amiram Eldar, Jan 16 2024 *)

Crossrefs

Cf. A000005.

Subsequence of A075027.

Sequence in context: A334799 A352287 A364462 * A108938 A085236 A068567

Adjacent sequences: A369179 A369180 A369181 * A369183 A369184 A369185

Keyword

nonn

Author

Zhicheng Wei, Jan 15 2024

Status

approved