Sum_{k=0..14} binomial(n,k).

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =32a(6) =64a(7) =128a(8) =256a(9) =512a(10) =1024a(11) =2048a(12) =4096a(13) =8192a(14) =16384a(15) =32767a(16) =65519a(17) =130918a(18) =261156a(19) =519252a(20) =1026876a(21) =2014992a(22) =3913704a(23) =7507638a(24) =14198086a(25) =26434916a(26) =48412432a(27) =87167164a(28) =154276028a(29) =268435456