OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..226
Zak Seidov, A175849,A175850
EXAMPLE
Some pairs of k,m: 1,1; 8,13; 9,12; 215,384; 458,575; 520,783; 2232,4095; 3251,4607; 3634,4095; 5349,6912; 9489,12543; 10051,13824.
MATHEMATICA
Select[Range[10^4], IntegerQ @ Sqrt[8*DivisorSigma[1, #*(#+1)/2] + 1] &] (* Amiram Eldar, Feb 23 2020 *)
PROG
(PARI) {for(n=1, 10^7, m=sigma(n*(n+1)/2); issquare(d=1+8*m) && print1(n, ", "))} \\ edited by
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Sep 27 2010
EXTENSIONS
More terms from Amiram Eldar, Feb 23 2020
STATUS
approved