This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A351012 #5 Feb 10 2022 20:18:48 %S A351012 1,0,1,1,3,3,5,6,9,10,13,16,21,24,29,35,43,50,60,70,83,97,113,132,156, %T A351012 178,206,239,275,316,365,416,477,545,620,706,806,912,1034,1173,1326, %U A351012 1496,1691,1902,2141,2410,2704,3034,3406,3808,4261,4765,5317,5932,6617 %N A351012 Number of even-length integer partitions y of n such that y_i = y_{i+1} for all even i. %e A351012 The a(2) = 1 through a(8) = 9 partitions: %e A351012 (11) (21) (22) (32) (33) (43) (44) %e A351012 (31) (41) (42) (52) (53) %e A351012 (1111) (2111) (51) (61) (62) %e A351012 (3111) (2221) (71) %e A351012 (111111) (4111) (2222) %e A351012 (211111) (3221) %e A351012 (5111) %e A351012 (311111) %e A351012 (11111111) %t A351012 Table[Length[Select[IntegerPartitions[n],EvenQ[Length[#]]&&And@@Table[#[[i]]==#[[i+1]],{i,2,Length[#]-1,2}]&]],{n,0,30}] %Y A351012 The ordered version (compositions) is A027383(n-2). %Y A351012 For odd instead of even indices we have A035363, any length A351004. %Y A351012 The version for unequal parts appears to be A122134, any length A122135. %Y A351012 This is the even-length case of A351003. %Y A351012 Requiring inequalities at odd positions gives A351007, any length A351006. %Y A351012 Cf. A000070, A018819, A035457, A088218, A101417, A122129, A350837, A351005, A351008. %K A351012 nonn %O A351012 0,5 %A A351012 _Gus Wiseman_, Feb 03 2022