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A126359 A sequence of prime numbers that can be expressed using only digits 0 and 1 in minimum ascending bases. 1
3, 5, 7, 37, 43, 223, 1297, 1303, 1549, 2801, 4673, 6571, 10111, 101111 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

3 = 10 base 3 = 3 + 0

5 = 10 base 5 = 5 + 0

7 = 11 base 6 = 6 + 1

37 = 101 base 6 = 36 + 0 + 1

43 = 111 base 6 = 36 + 6 + 1

223 = 1011 base 6 = 216 + 0 + 6 + 1

1297 = 10001 base 6 = 1296 + 0 + 0 + 0 + 1

1303 = 10011 base 6 = 1296 + 0 + 0 + 6 + 1

1549 = 11101 base 6 = 1296 + 216 + 36 + 0 + 1

2801 = 11111 base 7 = 2401 + 343 + 49 + 7 + 1

4673 = 11101 base 8 = 4096 + 512 + 64 + 0 + 1

6571 = 10011 base 9 = 6561 + 0 + 0 + 9 + 1

10111 = 10111 base 10 = 10000 + 0 + 100 + 10 + 1

101111 = 101111 base 10 = 100000 + 0 + 1000 + 100 + 10 + 1

LINKS

Table of n, a(n) for n=3..16.

FORMULA

Step 1: Starting at the first prime number (3), convert to the minimum base (3, as all primes may be expressed in binary).

Step 2: If the next prime number can be converted into the same base using only 0 and 1 without exceeding the value of the next prime number in the next base, this is the next item in the sequence.

Step 3: If the next prime number cannot be expressed in this base before exceeding the value of the next prime number in the next base, skip this prime number and move on to the next prime number and repeat Step 2.

Step 4: If the next prime number cannot be expressed in this base before exceeding the value of the next prime number in the next base, but can be expressed in the next base, this is the next item in the sequence.

EXAMPLE

2801 is a prime in this sequence in base 7. The next prime in base 7 is 17207 but this exceeds the value of a prime in base 8, such that A(n) (base y) < A(n+1) (base y+1) < A(n+1) (base y), so the next number in this sequence must go to the next base 8, which is 4673, because the number after 2081 in base 7 is 17207, and 4673 < 17207.

CROSSREFS

A215511

Sequence in context: A106115 A154544 A155034 * A182373 A087363 A234569

Adjacent sequences:  A126356 A126357 A126358 * A126360 A126361 A126362

KEYWORD

nonn,base

AUTHOR

Jason Betts, Aug 14 2012.

STATUS

approved

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Last modified August 14 21:07 EDT 2018. Contains 313756 sequences. (Running on oeis4.)