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A226944
Numbers k such that 1/k + Sum_{p|k} 1/p > 1.
1
30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360, 390, 420, 450, 462, 480, 510, 540, 546, 570, 600, 630, 660, 690, 714, 720, 750, 780, 798, 810, 840, 858, 870, 900, 924, 930, 960, 966, 990, 1020, 1050, 1080, 1092, 1110, 1140, 1170, 1200, 1218, 1230
OFFSET
1,1
COMMENTS
1/k + Sum_{p|k} 1/p = 1 when k is a primary pseudoperfect number (A054377).
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
fa=FactorInteger; A[n_] := Sum[1/fa[n][[i, 1]], {i, Length@fa@n}]; Select[1 + Range@1200, A[#] + 1/# > 1 &]
PROG
(PARI) is(n)=my(t=1-1/n); forprime(p=2, 97, if(n%p==0, n/=p^valuation(n, p); t-=1/p; if(t<0, return(1)))); if(n<101^ceil(101*t), return(0)); my(f=factor(n)[, 1]); t<sum(i=1, #f, 1/f[i]) \\ Charles R Greathouse IV, Dec 27 2013
CROSSREFS
Cf. A054377.
Sequence in context: A325992 A056954 A246947 * A249674 A050519 A358756
KEYWORD
nonn
AUTHOR
STATUS
approved