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URL: https://oeis.org/A140387

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A140387
Binary encoding of the location of primes in integer sets r+30*n with remainder r=1,7,11,..,29.
2
1, 32, 16, 129, 73, 36, 194, 6, 42, 176, 225, 12, 21, 89, 18, 97, 25, 243, 44, 44, 196, 34, 166, 90, 149, 152, 109, 66, 135, 225, 89, 169, 169, 28, 82, 210, 33, 213, 179, 170, 38, 92, 15, 96, 252, 171, 94, 7, 209, 2, 187, 22, 153, 9, 236, 197, 71, 179, 212, 197, 186
OFFSET
1,2
COMMENTS
Classify all integers 30n+r with r= 1, 7, 11, 13, 17, 19, 23 or 29 as nonprime or prime and assign bit positions 0=LSB, 1, 2, 3, .., 7=MSB to the 8 remainders in the same order. Raise the bit if 30n+r is nonprime, erase it if 30n+r is prime.
The sequence interprets this as a number in base 2 and shows the decimal representation.
EXAMPLE
For n=1, the 8 numbers 31 (r=1), 37 (r=7), 41 (r=11), 43 (r=17), 47 (r=17), 49 (r=19), 53 (r=23) and 59 (r=29) are prime, prime, prime, prime, prime, nonprime, prime, prime, prime, which is rendered into the binary 000100000 = 2^5=32=a(1).
CROSSREFS
Cf. A105052 (analog in base 10, prime = bit 1, remainder 1 = MSB), A140891 (analog in base 14, prime = bit 0, remainder 1 = LSB).
Sequence in context: A234967 A033352 A364904 * A023094 A087502 A070628
KEYWORD
nonn,base
AUTHOR
EXTENSIONS
Edited by R. J. Mathar, Jun 17 2008
STATUS
approved