cp's OEIS Frontend

A386968 Numbers that can be written in exactly four ways 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.

%I A386968 #16 Aug 16 2025 10:26:25
%S A386968 331979,536134,602342,848707,1007017,1360430,1484182,1767157,1891086,
%T A386968 2024074,2036922,2095031,2097159,2231826,2257754,2292303,2293830,
%U A386968 2320578,2440812,2503676,2590739,2744591,2852016,2890344,2914526,2944901,2951290,3019920,3020295,3053910,3121946,3157114,3310022
%N A386968 Numbers that can be written in exactly four ways 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.
%H A386968 David A. Corneth, <a href="/A386968/b386968.txt">Table of n, a(n) for n = 1..3353</a> (terms <= 10^8)
%e A386968 331979 = 2^15 + 4^5  + 5^6 + 6^7 + 7^4 + 15^2
%e A386968        = 2^2 + 3^8  + 4^9 + 5^3 + 8^4 + 9^5
%e A386968        = 2^5  + 3^10 + 4^9 + 5^2 + 9^3 + 10^4
%e A386968        = 2^6 + 3^10 + 4^9 + 5^5 + 6^2 + 9^4 + 10^3.
%e A386968 536134 = 2^6 + 3^12 + 4^3 + 5^5 + 6^4 + 12^2
%e A386968        = 2^16 + 3^10 + 4^9 + 5^7 + 6^6 + 7^5  + 9^4
%e A386968        = 2^16 + 4^8  + 5^5 + 6^7 + 7^6 + 8^4  + 16^2
%e A386968        = 2^18 + 3^11 + 4^4 + 5^7 + 7^5 + 11^3 + 18^2.
%e A386968 602342 = 2^16 + 3^12 + 4^4 + 5^5 + 12^3 + 16^2
%e A386968        = 2^8  + 3^12 + 4^3 + 5^5 + 6^6 + 8^2 + 12^4
%e A386968        = 2^13 + 3^8  + 4^2 + 5^3 + 6^7 + 7^5 + 8^6 + 13^4
%e A386968        = 2^15 + 3^10 + 4^8 + 5^7 + 6^4 + 7^2 + 8^6 + 10^5 + 15^3.
%e A386968 5260225 is not in the sequence as it can be written in exactly five ways a such. - _David A. Corneth_, Aug 16 2025
%Y A386968 Subsequence of A385969.
%Y A386968 Cf. A385232, A385233, A385970, A386966, A386967.
%K A386968 nonn
%O A386968 1,1
%A A386968 _Alberto Zanoni_, Aug 12 2025