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A114082
sigma(n) plus the n-th prime gives a square.
3
3, 6, 7, 9, 18, 58, 73, 134, 198, 251, 278, 287, 461, 483, 505, 525, 529, 665, 772, 939, 960, 986, 1291, 1432, 1463, 1629, 2115, 2931, 2991, 3422, 3888, 4159, 4231, 4548, 4715, 6256, 7867, 9148, 9474, 9540, 9958, 10535, 12035, 12081, 12223, 12511
OFFSET
1,1
LINKS
EXAMPLE
sigma(2115)+p(2115)=22201=149^2.
MATHEMATICA
n=0; p=1; seq={}; Do[p = NextPrime[p]; n++; If[IntegerQ @ Sqrt [p + DivisorSigma[1, n]], AppendTo[seq, n]], {10^4}]; seq (* Amiram Eldar, Aug 18 2019 *)
PROG
(PARI) isok(n) = issquare(sigma(n) + prime(n)); \\ Michel Marcus, Jan 11 2014
CROSSREFS
Sequence in context: A191187 A310134 A039591 * A343218 A185339 A189015
KEYWORD
nonn
AUTHOR
Giovanni Resta, Feb 13 2006
STATUS
approved