A390786 a(n) is the least k such that the number of integers between (1/5)*prime(k) and (1/5)*prime(k+1) is n.

2, 24, 30, 99, 189, 590, 217, 1879, 1831, 2810, 2225, 3644, 8688, 3385, 19026, 17006, 14357, 34215, 30802, 33608, 85633, 31545, 40933, 103520, 126172, 104071, 118505, 271743, 415069, 149689, 325852, 2078068, 1287544, 1736516, 2324140, 1094421, 4623702

Offset

1,1

Comments

See A390785 for a guide to related sequences. The sequence of primes indexed by this sequence is (3, 89, 113, 523, 1129, 4297, 1327, 16141, 15683, 25471, 19609, 34061, 89689, 31397, 212701, ...)

Links

Table of n, a(n) for n=1..37.

Mathematica

p[n_] := p[n] = Prime[n]; m = 5; z = 50000;
t = Table[Floor[p[n + 1]/m] - Floor[p[n]/m], {n, 1, z}];
Flatten[Table[First[Position[t, k]], {k, 1, 20}]]

Crossrefs

Cf. A390786, A390787, A390788.

Sequence in context: A349724 A022374 A139334 * A212759 A112660 A330526

Adjacent sequences: A390783 A390784 A390785 * A390787 A390788 A390789

Keyword

nonn

Author

Clark Kimberling, Nov 24 2025

Status

approved