A172335 Numbers k such that k and k+17 have same sum of divisors.

142, 238, 418, 429, 598, 622, 2985, 3502, 16269, 22678, 23188, 27778, 38494, 46761, 48489, 62235, 74188, 98745, 110170, 120345, 129448, 151677, 187822, 190888, 194818, 205185, 223685, 235438, 246934, 249166

Offset: 1

Author

Michel Lagneau, Feb 01 2010

Keywords

• nonn

References

• 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.
• J.-M. De Koninck, Ces nombres qui nous fascinent, Entry 62, p. 22, Ellipses, Paris 2008.
• W. Sierpiński, A Selection of Problems in the Theory of Numbers. Macmillan, NY, 1964, p. 110.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..500
• M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

Crossrefs

Cf. A000203.

Programs

Magma

[m:m in [1..250000]| SumOfDivisors(m) eq SumOfDivisors(m+17)]; // Marius A. Burtea, Aug 11 2019

Maple

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

Mathematica

Select[Range[10^5], DivisorSigma[1, #] == DivisorSigma[1, # + 17] &] (* Amiram Eldar, Aug 11 2019 *)