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 A071847 Numbers n such that sigma(n) - sigma(reverse(n)) = phi(n). 0
 1302, 6364, 13902, 30944, 35404, 57356, 88781, 132432, 141372, 183792, 284242, 555093, 806403, 1967262, 5010576, 5568948, 6298446, 7306241, 7496203, 7944911, 8078106 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE sigma(1302) - sigma(reverse(1302)) = sigma(1302) - sigma(2031) = 3072 - 2712 = 360 = phi(1302). MATHEMATICA r = {}; Do[ If[ DivisorSigma[1, n] - DivisorSigma[1, FromDigits[ Reverse[ IntegerDigits[n]]]] == EulerPhi[n], r = Append[r, n]], {n, 1, 10^7}]; r Select[Range[81*10^5], DivisorSigma[1, #]-DivisorSigma[ 1, IntegerReverse[ #]] == EulerPhi[#]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 08 2020 *) CROSSREFS Sequence in context: A107521 A226144 A250728 * A014356 A252308 A277772 Adjacent sequences:  A071844 A071845 A071846 * A071848 A071849 A071850 KEYWORD base,nonn AUTHOR Joseph L. Pe, Jun 09 2002 EXTENSIONS Edited and extended by Robert G. Wilson v, Jun 11 2002 STATUS approved

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Last modified May 17 17:52 EDT 2022. Contains 353778 sequences. (Running on oeis4.)