A048251 -id:A048251 - cp's OEIS frontend

A048253 a(n) is the number of integers whose sum of divisors is 6^n.

1, 1, 1, 5, 11, 18, 30, 48, 85, 148, 250, 415, 669, 1066, 1697, 2635, 4036, 6111, 9137, 13540, 19930, 29098, 42184, 60655, 86598, 122821, 173314, 243469, 340329, 473221, 654779, 901741, 1236668, 1689322, 2298592, 3115200, 4206016, 5658677, 7588039

Offset: 0

Labos Elemer

nonn

			For n=3, sigma(1,k) = 6^3 = 216 for each of 5 integers: 102, 110, 142, 159, and 187, so a(3) = 5.

Ray Chandler, Table of n, a(n) for n = 0..1000

Cf. A006532, A020477, A019422, A019423, A018427, A048251-A048256.

With[{s = Array[DivisorSigma[1, #] &, 6^8]}, Array[Count[s, 6^#] &, Log[6, Length@ s] + 1, 0]] (* Michael De Vlieger, May 14 2018 *)

a(n) = sum(k=1, 6^n, sigma(k)==6^n); \\ Michel Marcus, May 14 2018

a(9)-a(14) from Donovan Johnson, Sep 02 2008

Edited and extended by Ray Chandler, Sep 01 2010

A048255 Integers whose sum of divisors is 6^5 = 7776.

Original entry on oeis.org

3210, 3498, 3710, 3882, 3910, 4310, 4922, 4982, 5182, 5457, 5885, 6035, 6095, 6307, 6797, 7117, 7327, 7597

Offset: 1

Labos Elemer

Sequence has A048253(5)=18 terms from A048251(5)=3210 to A048252(5)=7597. - Ray Chandler

			Divisors of 7597 are {1,71,107,7597}, whose sum is 7776, so 7597 is in the sequence.

Cf. A006532, A020477, A019422, A019423, A018427, A048251-A048256.

Select[Range[7600],DivisorSigma[1,#]==7776&] (* Harvey P. Dale, Jun 04 2016 *)

for(i=1,t=6^5, sigma(i)==t & print1(i",")) \\ M. F. Hasler, Dec 09 2009

A048255 = { n | A000203(n)=6^5 }. - M. F. Hasler, Dec 09 2009

Minor edits, keywords added, and values checked with given PARI code by M. F. Hasler, Dec 09 2009

A048254 Numbers whose sum of divisors is 6^4 = 1296.

Original entry on oeis.org

510, 642, 710, 742, 782, 795, 862, 935, 1177, 1207, 1219

Offset: 1

Labos Elemer

Sequence has A048253(4)=11 terms from A048251(4)=510 to A048252(4)=1219. - Ray Chandler, Sep 01 2010

			The divisors of 1219 are 1, 23, 53, and 1219, whose sum is 1296, so 1219 is in the sequence.

Cf. A006532, A020477, A019422, A019423, A018427, A048251-A048256.

Select[Range[6^4], DivisorSigma[1, # ] == 6^4 &] (* Ray Chandler, Sep 01 2010 *)

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A048253 a(n) is the number of integers whose sum of divisors is 6^n.

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A048255 Integers whose sum of divisors is 6^5 = 7776.

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A048254 Numbers whose sum of divisors is 6^4 = 1296.

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Mathematica