A072955 Suburban numbers: without b, r, s or u.

1, 2, 5, 8, 9, 10, 11, 12, 15, 18, 19, 20, 21, 22, 25, 28, 29, 50, 51, 52, 55, 58, 59, 80, 81, 82, 85, 88, 89, 90, 91, 92, 95, 98, 99, 1000000, 1000001, 1000002, 1000005, 1000008, 1000009, 1000010, 1000011, 1000012, 1000015, 1000018, 1000019, 1000020

Offset: 1

Author

Michael Joseph Halm, Aug 13 2002

Keywords

• easy
• nonn
• word

References

• M. J. Halm, Sequences (Re)discovered, Mpossibilities 81 (Aug. 2002).

Links

• Michael S. Branicky, Table of n, a(n) for n = 1..10000
• Michael Halm, Sequences (Re)discovered.

Crossrefs

Cf. A089590, A072956, A072957.

Programs

Python

from num2words import num2words
from itertools import islice, product
def ok(n): return set(num2words(n)) & {"b", "r", "s", "u"} == set()
def agen(): # generator of terms < 10**304
    base, pows = [k for k in range(1, 1000) if ok(k)], [1]
    yield from ([0] if ok(0) else []) + base
    for e in range(3, 304, 3):
        if set(num2words(10**e)[4:]) & {"b", "r", "s", "u"} == set():
            pows = [10**e] + pows
            for t in product([0] + base, repeat=len(pows)):
                if t[0] == 0: continue
                yield sum(t[i]*pows[i] for i in range(len(t)))
print(list(islice(agen(), 66))) # Michael S. Branicky, Aug 19 2022