

A152864


Deficiency of n, plus the number of proper divisors of n: a(n) = 2n  sigma(n) + d(n)  1.


4



1, 2, 3, 3, 5, 3, 7, 4, 7, 5, 11, 1, 13, 7, 9, 5, 17, 2, 19, 3, 13, 11, 23, 5, 21, 13, 17, 5, 29, 5, 31, 6, 21, 17, 25, 11, 37, 19, 25, 3, 41, 5, 43, 9, 17, 23, 47, 19, 43, 12, 33, 11, 53, 5, 41, 1, 37, 29, 59, 37, 61, 31
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OFFSET

1,2


LINKS



FORMULA



MATHEMATICA

a[n_] := 2*n  Differences[DivisorSigma[{0, 1}, n]][[1]]  1; Array[a, 100] (* Amiram Eldar, Apr 07 2024 *)


PROG

(PARI) a(n) = 2*n  sigma(n) + numdiv(n)  1; \\ Amiram Eldar, Apr 07 2024


CROSSREFS



KEYWORD

easy,sign


AUTHOR



STATUS

approved



