A213059 Subsets of positive integers arranged in canonical order.
1, 12, 2, 123, 13, 23, 3, 1234, 124, 134, 234, 14, 24, 34, 4, 12345, 1235, 1245, 1345, 2345, 125, 135, 145, 235, 245, 345, 15, 25, 35, 45, 5, 123456, 12346, 12356, 12456, 13456, 23456, 1236, 1246, 1256, 1346, 1356, 1456, 2346, 2356, 2456, 3456, 126, 136, 146, 156, 236, 246, 256, 346, 356, 456, 16, 26, 36, 46, 56, 6
Offset: 1
Keywords
Links
- Michael S. Branicky, Table of n, a(n) for n = 1..10000
- T. Kubo and R. Vakil, On Conway's recursive sequence, Discr. Math. 152 (1996), 225-252. a(n) is the concatenation of their S(n).
Crossrefs
Cf. A030299.
Programs
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Python
from itertools import chain, combinations as C def powerset(s): # in decreasing size return chain.from_iterable(C(s, r) for r in range(len(s), -1, -1)) def agen(): m = 1 # largest element while True: for p in powerset(range(1, m)): yield int("".join(map(str, p+(m,)))) m += 1 def aupton(terms): alst, g = [], agen() while len(alst) < terms: alst += [next(g)] return alst print(aupton(63)) # Michael S. Branicky, Jan 12 2021
Extensions
a(25) corrected by Michael S. Branicky, Jan 12 2021
Comments