A385969 Numbers that can be written as s_1^x_1 + ... + s_t^x_t, with 1 < s_1 < ... < s_t and {s_1,..., s_t} = {x_1,..., x_t} for some t > 0.

4, 17, 27, 31, 32, 57, 59, 84, 89, 100, 105, 127, 145, 149, 166, 177, 202, 204, 245, 254, 256, 260, 273, 276, 283, 287, 289, 313, 320, 322, 340, 347, 348, 356, 368, 372, 377, 383, 400, 422, 433, 460, 465, 468, 480, 532, 545, 548, 568, 576, 593, 603, 620, 624, 628, 673, 688, 700

Offset: 1

Author

Alberto Zanoni, Jul 13 2025

Keywords

• nonn

Comments

The value 1 is excluded because for t = 2 one would obtain 1^x_1 + x_1^1 = 1 + x_1, which for x_1 = 2,3,4,... would give the trivial sequence 3,4,5,6,...

Examples

			a(1) =  4 : 2^2 = 4 (t = 1)
a(2) = 17 : 2^3 + 3^2 = 8 + 9 = 17 (t = 2)
a(3) = 27 : 3^3 = 27 (t = 1)
a(4) = 31 : 2^2 + 3^3 = 4 + 27 = 31 (t = 2)
		

Links

• David A. Corneth, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A385232, A385233, A385970.