OFFSET
1,3
MATHEMATICA
a[1] = a[2] = 1; a[n_] := a[n] = DivisorSigma[1, a[n - 1] + a[n - 2]]; Table[a[n], {n, 27}]
RecurrenceTable[{a[1]==a[2]==1, a[n]==DivisorSigma[1, a[n-1]+a[n-2]]}, a, {n, 30}] (* Harvey P. Dale, Feb 15 2015 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Joseph L. Pe, Apr 08 2002
EXTENSIONS
Edited and extended by Robert G. Wilson v, Apr 11 2002
STATUS
approved