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A225757
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Table of consecutive numbers with the same sum of divisors.
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3
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14, 15, 206, 207, 957, 958, 1334, 1335, 1364, 1365, 1634, 1635, 2685, 2686, 2974, 2975, 4364, 4365, 14841, 14842, 18873, 18874, 19358, 19359, 20145, 20146, 24957, 24958, 33998, 33999, 36566, 36567, 42818, 42819, 56564, 56565, 64665, 64666, 74918, 74919, 79826
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OFFSET
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1,1
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COMMENTS
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Are 3 consecutive terms possible? There are none less than 10^12. See A002961. - T. D. Noe, May 15 2013
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LINKS
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EXAMPLE
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Sequence begins:
14, 15;
206, 207;
957, 958;
1334, 1335;
etc.
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MATHEMATICA
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sel = Select[Range[100000], DivisorSigma[1, #] == DivisorSigma[1, # + 1] &]; Union[sel, sel + 1]
Flatten[SequencePosition[DivisorSigma[1, Range[80000]], {x_, x_}]] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Oct 13 2017 *)
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PROG
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(PARI) v=List(); t=[1, 3]; for(n=3, 1e6, t=[t[2], sigma(n)]; if(t[1]==t[2], listput(v, n-1); listput(v, n))); vecsort(Vec(v), , 8) \\ Charles R Greathouse IV, May 15 2013
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CROSSREFS
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Cf. A225756 (same number of divisors), A225758 (same number and sum of divisors), A002961 (first number of each pair).
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KEYWORD
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nonn,tabf
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AUTHOR
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STATUS
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approved
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