A353346 Numbers k such that the elements of the continued fraction of the abundancy index of k and k+1 are anagrams of each other.

2084564, 11784194, 13667268, 52820326, 68397891, 101183694, 128247668, 135641787, 137681487, 170542955, 266319572, 284966486, 384109196, 386860419, 482419526, 483785771, 546800667, 579468939, 606809224, 622241109, 703636544, 737703005, 829965829, 830993564, 834224684, 973986250

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..108

Example

2084564 is a term since the sequences of elements of the continued fractions of sigma(2084564)/2084564 = 941472/521141 and sigma(2084565)/2084565 = 1270656/694855, {1, 1, 4, 5, 1, 8, 1, 5, 2, 4, 1, 7, 3} and {1, 1, 4, 1, 5, 8, 1, 2, 4, 7, 3, 1, 5} respectively, are anagrams of each other.

Mathematica

ab[n_] := Sort[ContinuedFraction[DivisorSigma[-1, n]]]; seq[max_] := Module[{s = {}, n = 2, c = 0, ab1 = ab[1], ab2}, While[n < max, ab2 = ab[n]; If[ab1 == ab2, AppendTo[s, n - 1]]; ab1 = ab2; n++]; s]; seq[1.4*10^7]

Crossrefs

Cf. A000203 (sigma), A069567, A017665, A017666, A349685, A353345, A353347.

Sequence in context: A155126 A234469 A212728 * A234420 A115505 A126435

Adjacent sequences: A353343 A353344 A353345 * A353347 A353348 A353349

Keyword

nonn

Author

Amiram Eldar, Apr 15 2022

Status

approved