Number of compositions of n such that two adjacent parts are not equal modulo 4.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =4a(5) =7a(6) =12a(7) =22a(8) =33a(9) =57a(10) =103a(11) =169a(12) =277a(13) =479a(14) =824a(15) =1368a(16) =2306a(17) =3941a(18) =6657a(19) =11206a(20) =18998a(21) =32194a(22) =54325a(23) =91880a(24) =155633a(25) =263120a(26) =444674a(27) =752545a(28) =1273278a(29) =2152704