A225758 Runs of consecutive numbers with the same number and sum of divisors.

14, 15, 1334, 1335, 1634, 1635, 2685, 2686, 33998, 33999, 42818, 42819, 64665, 64666, 84134, 84135, 109214, 109215, 122073, 122074, 166934, 166935, 289454, 289455, 383594, 383595, 440013, 440014, 544334, 544335, 605985, 605986, 649154, 649155, 655005, 655006

Offset

1,1

Comments

No triple found up to 10^9.

Links

Donovan Johnson, Table of n, a(n) for n = 1..1000

Example

Sequence begins:
14, 15;
1334, 1335;
1634, 1635;
2685, 2686;
33998, 33999;
etc.

Mathematica

sel = Select[Range[1000000], DivisorSigma[0, #] == DivisorSigma[0, #+1] && DivisorSigma[1, #] == DivisorSigma[1, #+1] &]; Union[sel, sel+1]

Crossrefs

Cf. A225756 (same number of divisors), A225757 (same sum of divisors).

Cf. A054004 (first term of every run).

Sequence in context: A041417 A041418 A042733 * A351866 A043663 A043703

Adjacent sequences: A225755 A225756 A225757 * A225759 A225760 A225761

Keyword

nonn,easy

Author

Jean-François Alcover, May 15 2013

Status

approved