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a(n) = a(n-1) + c(n+1) for n >= 3, a( ) increasing, given a(1)=1, a(2)=7; where c( ) is complement of a( ).
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%I #9 Apr 05 2016 07:31:12

%S 1,7,12,18,26,35,45,56,69,83,98,114,131,150,170,191,213,236,260,285,

%T 312,340,369,399,430,462,495,529,565,602,640,679,719,760,802,845,889,

%U 935,982,1030,1079,1129,1180,1232,1285,1339,1394,1451,1509,1568

%N a(n) = a(n-1) + c(n+1) for n >= 3, a( ) increasing, given a(1)=1, a(2)=7; where c( ) is complement of a( ).

%C Here "complement" refers to the numbers not in the sequence.

%H Ivan Neretin, <a href="/A022953/b022953.txt">Table of n, a(n) for n = 1..10000</a>

%t Fold[Append[#1, #1[[-1]] + Complement[Range[Max@#1 + 3], #1][[#2 + 1]]] &, {1, 7}, Range[3, 50]] (* _Ivan Neretin_, Apr 05 2016 *)

%Y Essentially same as A005228.

%K nonn

%O 1,2

%A _Clark Kimberling_