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a(n) = A002952(n) + A002953(n).
1

%I #15 Jul 29 2024 09:59:27

%S 240,2400,40320,72576,94080,120960,141120,311040,403200,483840,483840,

%T 725760,673920,1010880,1209600,1497600,1411200,1612800,1747200,

%U 2246400,2177280,2371200,2449440,2419200,2620800,2903040,3144960,3110400

%N a(n) = A002952(n) + A002953(n).

%H Amiram Eldar, <a href="/A180277/b180277.txt">Table of n, a(n) for n = 1..7896</a>

%F a(n) = A002952(n) + A002953(n).

%F {(j+k) such that sigma*(j) = sigma*(k) = j+k, where sigma*(n) is the unitary divisor function A034448}.

%e a(1) = 114 + 126 = 240 = 2^4 * 3 * 5.

%e a(2) = 1140 + 1260 = 2400 = 2^5 * 3 * 5^2.

%e a(10) = a(11) - why?

%Y Cf. A002952, A002953, A161005, A180163.

%K nonn,less

%O 1,1

%A _Jonathan Vos Post_, Aug 23 2010

%E Extended by _R. J. Mathar_, Aug 26 2010

%E Shorter name using given formula from _Joerg Arndt_, Jul 29 2024