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A172335 Numbers n such that n and n+17 have same sum of divisors. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

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. SierpiƄski, 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].

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 *)

PROG

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

CROSSREFS

Cf. A000203.

Sequence in context: A025379 A202279 A035702 * A217531 A158135 A092230

Adjacent sequences:  A172332 A172333 A172334 * A172336 A172337 A172338

KEYWORD

nonn

AUTHOR

Michel Lagneau, Feb 01 2010

STATUS

approved

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Last modified May 6 23:10 EDT 2021. Contains 343599 sequences. (Running on oeis4.)