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A139423
a(1)=1, a(2)=2. For n >= 3, a(n) = a(n-1) + d(a(n-1)) + d(a(n-2)), where d(m) is the number of positive divisors of m.
1
1, 2, 5, 9, 14, 21, 29, 35, 41, 47, 51, 57, 65, 73, 79, 83, 87, 93, 101, 107, 111, 117, 127, 135, 145, 157, 163, 167, 171, 179, 187, 193, 199, 203, 209, 217, 225, 238, 255, 271, 281, 285, 295, 307, 313, 317, 321, 327, 335, 343
OFFSET
1,2
MAPLE
with(numtheory): a[1]:=1: a[2]:=2: for n from 3 to 50 do a[n]:=a[n-1]+tau(a[n-1])+tau(a[n-2]) end do: seq(a[n], n=1..50); # Emeric Deutsch, Apr 30 2008
MATHEMATICA
Join[{a = 1, b = 2}, Table[c = b + Total[DivisorSigma[0, {a, b}]]; a = b; b = c; c, {n, 48}]] (* Jayanta Basu, Jun 06 2013 *)
CROSSREFS
Sequence in context: A191170 A191123 A152888 * A363459 A026053 A276031
KEYWORD
nonn
AUTHOR
Leroy Quet, Apr 21 2008
EXTENSIONS
More terms from Emeric Deutsch, Apr 30 2008
STATUS
approved