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 A228519 Numbers n such that sigma(n) = sigma(n - phi(n)), where sigma(n) is the sum of divisors of n and phi(n) is the Euler totient function of n. 1
 9356, 52412, 110442, 160834, 220884, 266866, 289230, 321668, 420790, 441768, 533732, 556818, 578460, 643336, 731530, 841580, 883536, 1067464, 1113636, 1156920, 1286672, 1446150, 1463060, 1683160, 1767072, 2103950, 2134928, 2227272, 2313840, 2545888, 2573344, 2892300 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..1000 FORMULA sigma(9356- phi(9356)) = sigma(9356 - 4676) = 16380 = sigma(9356). MAPLE with(numtheory); P:=proc(q) local n; for n from 1 to q do if sigma(n)=sigma(n-phi(n)) then print(n); fi; od; end: P(10^9); MATHEMATICA Select[Range[10^6], DivisorSigma[1, #] == DivisorSigma[1, # - EulerPhi@ #] &] (* Michael De Vlieger, Jun 21 2016 *) CROSSREFS Cf. A000010, A000203, A051953, A067880. Sequence in context: A004954 A004974 A251824 * A292283 A265457 A330902 Adjacent sequences:  A228516 A228517 A228518 * A228520 A228521 A228522 KEYWORD nonn,easy AUTHOR Paolo P. Lava, Jun 21 2016 STATUS approved

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Last modified January 24 07:51 EST 2022. Contains 350534 sequences. (Running on oeis4.)