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 A303993 Numbers whose sum of divisors is the cube of one of their divisors. 6
 1, 102, 8148, 63720, 66120, 71880, 196896, 446040, 452760, 462840, 471960, 503160, 517320, 544920, 549240, 554280, 559320, 575880, 756400, 1458912, 1499232, 1579872, 1634040, 1659960, 1748520, 5294800, 9740640, 10103520, 11103456, 11438280, 11583264, 11619720, 11915640 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Subset of A020477. LINKS Table of n, a(n) for n=1..33. EXAMPLE Divisors of 102 are 1, 2, 3, 6, 17, 34, 51, 102 and their sum is 216 = 6^3. MAPLE with(numtheory): P:=proc(q) local a, k, n; for n from 1 to q do a:=sort([op(divisors(n))]); for k from 1 to nops(a) do if sigma(n)=a[k]^3 then print(n); break; fi; od; od; end: P(10^9); MATHEMATICA Select[Range[10^6], Mod[#, DivisorSigma[1, #]^(1/3)] == 0 &] (* Michael De Vlieger, May 06 2018 *) PROG (PARI) isok(n) = (n==1) || (ispower(s=sigma(n), 3) && !(n % sqrtnint(s, 3))); \\ Michel Marcus, May 05 2018 CROSSREFS Cf. A000203, A020477, A303123, A303994, A303995, A303996. Sequence in context: A217331 A284448 A274252 * A030512 A097725 A353142 Adjacent sequences: A303990 A303991 A303992 * A303994 A303995 A303996 KEYWORD nonn,easy AUTHOR Paolo P. Lava, May 04 2018 STATUS approved

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Last modified June 22 14:17 EDT 2024. Contains 373587 sequences. (Running on oeis4.)