Start with Pascal's triangle; a(n) is the sum of the numbers on the periphery of the n-th central rhombus containing exactly 4 numbers.

A081496

Start with Pascal's triangle; a(n) is the sum of the numbers on the periphery of the n-th central rhombus containing exactly 4 numbers.

Terms

    a(0) =5a(1) =14a(2) =46a(3) =160a(4) =574a(5) =2100a(6) =7788a(7) =29172a(8) =110110a(9) =418132a(10) =1595620a(11) =6113744a(12) =23505356a(13) =90633800a(14) =350351640a(15) =1357278300a(16) =5268292830a(17) =20483876820a(18) =79765662900a(19) =311038321440

External references