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 A278474 Numbers n such that the product of proper divisors of n ends with n and n is not a multiplicatively perfect number (A007422). 0
 24, 36, 76, 375, 376, 432, 624, 625, 693, 875, 999, 2499, 4557, 8307, 9375, 9376, 9999, 34375, 40625, 47943, 50001, 59375, 81249, 90624, 90625, 99999, 109376, 186432, 218751, 586432, 609375, 690624, 718751, 781249, 890625, 954193, 968751, 999999, 2109375, 2890624, 2890625 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers n such that A007956(n) == n (mod A011557(A055642(n))) and A000005(n) <> 4. LINKS Eric Weisstein's World of Mathematics, Divisor Product EXAMPLE 24 is in the sequence because 24 has 7 proper divisors {1,2,3,4,6,8,12} and 1*2*3*4*6*8*12 = 13824; 36 is in the sequence because 36 has 8 proper divisors {1,2,3,4,6,9,12,18} and 1*2*3*4*6*9*12*18 = 279936; 76 is in the sequence because 76 has 5 proper divisors {1,2,4,19,38} and 1*2*4*19*38 = 5776, etc. MATHEMATICA Select[Range[3000000], Mod[Sqrt[#1]^DivisorSigma[0, #1]/#1, 10^IntegerLength[#1]] == #1 && Sqrt[#1]^DivisorSigma[0, #1] != #1^2 & ] CROSSREFS Cf. A000005, A007422, A007956, A011557, A055642, A210994 Sequence in context: A261022 A179152 A193069 * A288949 A108190 A185489 Adjacent sequences:  A278471 A278472 A278473 * A278475 A278476 A278477 KEYWORD nonn,base AUTHOR Ilya Gutkovskiy, Nov 23 2016 STATUS approved

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Last modified October 17 22:48 EDT 2018. Contains 316297 sequences. (Running on oeis4.)