A119746 Sum of previous term and preceding relatively prime terms.
1, 2, 3, 6, 7, 19, 38, 49, 118, 197, 440, 716, 992, 1268, 1544, 1820, 2040, 2313, 9524, 12113, 33210, 45596, 60298, 74944, 89646, 102032, 116678, 129067, 684624, 826077, 1219334, 2189180, 2203807, 7807703, 15615406, 18789059, 50019871, 100039302
Offset: 1
Keywords
Crossrefs
Cf. A120610.
Programs
-
Mathematica
s={1,2};Do[AppendTo[s,s[[-1]]+Total[Select[s,CoprimeQ[#,s[[-1]]]&]]],{n,36}];s (* James C. McMahon, Feb 24 2025 *)
Formula
a(1)=1, a(2)=2, for n>=2, a(n+1) = a(n) + Sum_{1<=k
A120611 Sum of previous term and preceding divisors.
1, 2, 3, 4, 7, 8, 15, 19, 20, 27, 31, 32, 47, 48, 66, 72, 90, 111, 115, 116, 123, 127, 128, 175, 183, 187, 188, 242, 245, 253, 254, 384, 610, 613, 614, 617, 618, 624, 690, 826, 836, 862, 865, 866, 869, 870, 891, 922, 925, 926, 929, 930, 982, 985, 986, 989, 990
Offset: 1
Keywords
Links
- Ivan Neretin, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
a = {1, 2}; Do[AppendTo[a, Plus @@ Intersection[a, Divisors[a[[-1]]]]], {n, 3, 57}]; a (* Ivan Neretin, May 13 2015 *)
Formula
a(1) = 1, a(2) = 2, for n>=2, a(n+1) = a(n) + sum_{1<=k