A024784 Every suffix prime and no 0 digits in base 9 (written in base 9).

2, 3, 5, 7, 12, 25, 32, 45, 47, 52, 65, 67, 87, 212, 232, 267, 287, 425, 432, 447, 465, 625, 667, 812, 832, 847, 867, 887, 2287, 2432, 4212, 4465, 4667, 4832, 4847, 4887, 6212, 6267, 6425, 6832, 6887, 8287, 8447, 8667, 8812, 22287, 24465, 24847, 26212, 26887

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base
• easy
• fini
• full

Comments

The final term of the sequence is a(108) = 4284484465.

Links

• Nathaniel Johnston, Table of n, a(n) for n = 1..108 (full sequence)

Crossrefs

Cf. A024779, A024780, A024781, A024782, A024783, A024785.

Programs

Maple

a:=[[2],[3],[5],[7]]: l1:=1: l2:=4: do for k from 1 to 8 do for j from l1 to l2 do d:=[op(a[j]),k]: if(isprime(op(convert(d, base, 9, 9^nops(d)))))then a:=[op(a), d]: fi: od: od: l1:=l2+1: l2:=nops(a): if(l1>l2)then break: fi: od: seq(op(convert(a[j], base, 10, 10^nops(a[j]))), j=1..nops(a)); # Nathaniel Johnston, Jun 21 2011

Python

from sympy import isprime
def afull():
    prime9strings, alst = list("2357"), []
    while len(prime9strings) > 0:
        alst.extend(sorted(int(p) for p in prime9strings))
        candidates = set(d+p for p in prime9strings for d in "12345678")
        prime9strings = [c for c in candidates if isprime(int(c, 9))]
    return alst
print(afull()) # Michael S. Branicky, Apr 27 2022