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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 (list; graph; refs; listen; history; text; internal format)
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], 2013-2014 (see page 6).

Tim Trudgian, The sum of the unitary divisor function, Publications de l'Institut Mathématique (Beograd), Vol. 97(111), 2015.

EXAMPLE

The e-divisors 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

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Last modified July 30 08:54 EDT 2021. Contains 346355 sequences. (Running on oeis4.)