A180277 - OEIS

A180277

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

240, 2400, 40320, 72576, 94080, 120960, 141120, 311040, 403200, 483840, 483840, 725760, 673920, 1010880, 1209600, 1497600, 1411200, 1612800, 1747200, 2246400, 2177280, 2371200, 2449440, 2419200, 2620800, 2903040, 3144960, 3110400

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OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..7896

FORMULA

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

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

EXAMPLE

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

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

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

CROSSREFS

Cf. A002952, A002953, A161005, A180163.

Sequence in context: A049335 A004009 A269033 * A357257 A005950 A279746

Adjacent sequences: A180274 A180275 A180276 * A180278 A180279 A180280

KEYWORD

nonn,less

AUTHOR

Jonathan Vos Post, Aug 23 2010

EXTENSIONS

Extended by R. J. Mathar, Aug 26 2010

Shorter name using given formula from Joerg Arndt, Jul 29 2024

STATUS

approved