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

Author

Michel Marcus, Jan 29 2014

Keywords

• nonn
• more

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.

Examples

			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.
		

Links

• 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.

Crossrefs

Cf. A034448, A051377.

Extensions

More terms from Andrew Lelechenko, Feb 06 2014