OFFSET
2,3
LINKS
Antti Karttunen, Table of n, a(n) for n = 2..16385
FORMULA
EXAMPLE
a(12) = sigma(12) - 23 = 28 - 23 = 5.
MAPLE
A202111 := proc(n)
A049711(numtheory[sigma](n) );
end proc:
seq(A202111(n), n=2..80) ; # R. J. Mathar, Dec 13 2011
MATHEMATICA
f[n_]:=Module[{nf=DivisorSigma[1, n]}, nf-NextPrime[nf, -1]]; f/@Range[3, 90]
PROG
(PARI)
A049711(n) = (n-precprime(n-1)); \\ This function from M. F. Hasler, Sep 09 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Dec 11 2011
EXTENSIONS
More terms from Antti Karttunen, Nov 07 2017
STATUS
approved