A226363 Oblong numbers (A002378) whose sum of divisors is also an oblong number.

6, 20, 30, 306, 1722, 2862, 11772, 13572, 28730, 29756, 40602, 54056, 219492, 351056, 463080, 947702, 1391220, 1546292, 2043470, 7174362, 7703400, 11400752, 15104882, 19127502, 20155610, 113667582, 172173762, 314299712, 475654290, 555238532, 558447792, 562519806

Offset

1,1

Links

Donovan Johnson, Table of n, a(n) for n = 1..200

Mathematica

oblongQ[n_] := IntegerQ[(-1 + Sqrt[1 + 4*n])/2]; s = Select[Range[24000], oblongQ[DivisorSigma[1, # (# + 1)]] &]; s * (s + 1) (* T. D. Noe, Jun 12 2013 *)

Crossrefs

Cf. A000203, A002378, A083674.

Sequence in context: A242341 A140738 A325593 * A253906 A031005 A106528

Adjacent sequences: A226360 A226361 A226362 * A226364 A226365 A226366

Keyword

nonn

Author

Alex Ratushnyak, Jun 05 2013

Status

approved