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# SAGE
(SageMath)
def matrix_entry(L1, L2, n):
.... tally=0
.... for i in range(n-1):
........ if (not i in L1) and (not i in L2) and (not i+1 in L1) and (not i+1 in L2):
............ tally+=1
.... return 2^tally
.... index_set={}
.... counter=0
.... for C in Combinations(n):
........ index_set[counter]=C
........ counter+=1
.... current_v=[0]*counter
.... current_v[0]=1
.... for t in range(n):
........ new_v=[0]*counter
........ for i in range(counter):
............ for j in range(counter):
................ new_v[i]+=current_v[j]*matrix_entry(index_set[iI], index_set[j], n)
........ current_v=new_v
.... return current_v[0]
for n in range(0, 10):
print(a(n), end=', ')
approved
editing
Steve Butler, <a href="/A254127/b254127_1.txt">Table of n, a(n) for n = 0..15</a>
editing
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Main diagonal of A254414.
Steve Butler, <a href="/A254127/b254127_1.txt">Table of n, a(n) for n = 10..1415</a>
1, 1, 7, 257, 50128, 50796983, 264719566561, 7063448084710944, 963204439792722969647, 670733745303300958404439297, 2384351527902618144856749327661056, 43263422878945294225852497665519673400479, 4006622856873663241294794301627790673728956619649
1,2
0,3
a(0)=1 prepended by Alois P. Heinz, Jan 30 2015
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editing
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