

A056996


Positive integers not of the form sigma(k) + phi(k)  2k for some k.


5



5, 11, 19, 21, 23, 27, 33, 35, 39, 43, 45, 47, 51, 53, 55, 59, 67, 69, 71, 79, 81, 83, 87, 95, 99, 101, 103, 105, 107, 113, 115, 117, 119, 123, 129, 131, 135, 139, 141, 143, 147, 151, 153, 155, 159, 165, 167, 171, 173, 175, 177, 179, 185, 187, 189, 191, 193, 195
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OFFSET

1,1


COMMENTS

Under the assumption that every even integer >= 18 is the sum of three distinct primes, all elements of this sequence are odd. See A278373 for more details.


LINKS

David W. Wilson, Table of n, a(n) for n = 1..10000


MATHEMATICA

Take[#, 59] &@ Complement[Range@ #, Union@ Table[DivisorSigma[1, n] + EulerPhi@ n  2 n, {n, #}]] &[10^5] (* Michael De Vlieger, Nov 30 2016 *)


CROSSREFS

Complement is A278373.
Cf. A000010 (phi), A000203 (sigma).
Sequence in context: A048253 A102174 A140515 * A102184 A290751 A320518
Adjacent sequences: A056993 A056994 A056995 * A056997 A056998 A056999


KEYWORD

nonn


AUTHOR

David W. Wilson, Sep 06 2000


STATUS

approved



