

A236474


Numbers such that the sum of unitary divisors (A034448) is equal to the sum of exponential divisors (A051377).


1



1, 20, 45, 320, 6615, 382200, 680890228200, 8169778639360, 27445575588992, 56626123593600, 1235050901504640
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OFFSET

1,2


COMMENTS

Following numbers also belongs to this sequence, however their actual positions are unknown: 3640527948039840, 181552482521182080, 19736989888296320640, 108455561012908979640, 796015410768776072160, 4220107447484548287360, 39697147230528075361920, 202868762331595335655680, 668431747385354202124160, 124402428235930297906738935, 2456687209744634987008753664.


LINKS

Table of n, a(n) for n=1..11.
Tim Trudgian, The sum of the unitary divisor function, arXiv:1312.4615 [math.NT], 20132014 (see page 6).
Tim Trudgian, The sum of the unitary divisor function, Publications de l'Institut MathÃ©matique (Beograd), Vol. 97(111), 2015.


EXAMPLE

The edivisors of 20 are 10 and 20, sum 30, and its unitary divisors are 1, 4, 5, and 20, also sum 30.
For n=320=2^6*5 we have A051377(n)=(2^6+2^3+2^2+2)*5 = 390 and A034448(n)=(2^6+1)*(5+1) = 390 again.


CROSSREFS

Cf. A034448, A051377.
Sequence in context: A044097 A044478 A228319 * A145220 A234266 A234259
Adjacent sequences: A236471 A236472 A236473 * A236475 A236476 A236477


KEYWORD

nonn,more


AUTHOR

Michel Marcus, Jan 29 2014


EXTENSIONS

More terms from Andrew Lelechenko, Feb 06 2014


STATUS

approved



