This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
- 1 = 2^0, so 1 is not a term, - 2 = 2^1, so 2 is not a term, - a(1) = 3 (as 3 is not a power of 2), - 4 = 2^2, so 4 is not a term, - 3 + 5 = 2^3, so 5 is not a term, - a(2) = 6 (as neither 6 nor 3 + 6 is a power of 2), - 3 + 6 + 7 = 2^4, so 7 is not a term, - 8 = 2^3, so 8 is not a term, - a(3) = 9 (as none of 9, 3 + 9, 6 + 9, 3 + 6 + 9 is a power of 2).
from math import gcd
from itertools import count, islice
def agen(): # generator of terms
a, ss, pows2, m = [], set(), {1, 2}, 2
for k in count(1):
if k in pows2: continue
elif k > m: m <<= 1; pows2.add(m)
if any(p2-k in ss for p2 in pows2): continue
a.append(k); yield k
ss |= {k} | {k+si for si in ss if k+si not in ss}
while m < max(ss): m <<= 1; pows2.add(m)
print(list(islice(agen(), 32))) # Michael S. Branicky, Jun 09 2023
Comments