A236474 Numbers such that the sum of unitary divisors (A034448) is equal to the sum of exponential divisors (A051377).

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

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