

A226944


Numbers n such that 1/n + sum_{pn} 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
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OFFSET

1,1


COMMENTS

sum(pn,1/p) + 1/n =1 for the primary pseudoperfect numbers (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=11/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 A069819
Adjacent sequences: A226941 A226942 A226943 * A226945 A226946 A226947


KEYWORD

nonn


AUTHOR

José María Grau Ribas, Jun 23 2013


STATUS

approved



