a(n) is the number of 2 X 2 matrices with entries in {1, ..., n} that are not the product of two 2 X 2 positive integer matrices.

A260550

a(n) is the number of 2 X 2 matrices with entries in {1, ..., n} that are not the product of two 2 X 2 positive integer matrices.

Terms

    a(0) =1a(1) =15a(2) =75a(3) =237a(4) =559a(5) =1157a(6) =2055a(7) =3471a(8) =5449a(9) =8131a(10) =11633a(11) =16361a(12) =22041a(13) =29349a(14) =38329a(15) =48839a(16) =61325a(17) =76479a(18) =93957a(19) =114717a(20) =138041a(21) =164153a(22) =194505a(23) =229625a(24) =268259a(25) =311031a(26) =359719a(27) =413245a(28) =472145a(29) =537835

External references