A172335 - OEIS

%I #17 Sep 08 2022 08:45:50

%S 142,238,418,429,598,622,2985,3502,16269,22678,23188,27778,38494,

%T 46761,48489,62235,74188,98745,110170,120345,129448,151677,187822,

%U 190888,194818,205185,223685,235438,246934,249166

%N Numbers n such that n and n+17 have same sum of divisors.

%D M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 840.

%D J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 62, p. 22, Ellipses, Paris 2008.

%D W. Sierpiński, A Selection of Problems in the Theory of Numbers. Macmillan, NY, 1964, p. 110.

%H Amiram Eldar, <a href="/A172335/b172335.txt">Table of n, a(n) for n = 1..500</a>

%H M. Abramowitz and I. A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

%p with(numtheory):for n from 1 to 250000 do;if sigma(n) = sigma(n+17) then print(n); else fi ; od;

%t Select[Range[10^5], DivisorSigma[1, #] == DivisorSigma[1, # + 17] &] (* _Amiram Eldar_, Aug 11 2019 *)

%o (Magma) [m:m in [1..250000]| SumOfDivisors(m) eq SumOfDivisors(m+17)]; // _Marius A. Burtea_, Aug 11 2019

%Y Cf. A000203.

%K nonn

%O 1,1

%A _Michel Lagneau_, Feb 01 2010