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A133155 Numbers formed by setting bits representing odd primes, where bit_no = (prime - 1)/2. Setting bit number b is the same as OR-ing with 2^b (i.e., bit numbers start at zero). 0
2, 6, 14, 46, 110, 366, 878, 2926, 19310, 52078, 314222, 1362798, 3459950, 11848558, 78957422, 615828334, 1689570158, 10279504750, 44639243118, 113358719854, 663114533742, 2862137789294, 20454323833710, 301929300544366 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..24.

FORMULA

a(n) = setbit(a(n-1),(p-1)/2) where p is the n-th odd prime.

EXAMPLE

a(3) = 14 because 3, 5 and 7 are odd primes so therefore bits 1, 2 and 3 are set and bit zero is not. 1110_2 = 14.

PROG

#!/usr/bin/python import gmpy a = gmpy.mpz(0) i = 0 for p in range(3, 100, 2): if gmpy.is_prime(p): a = gmpy.setbit(a, (p-1)/2) i += 1 print i, a

CROSSREFS

Sequence in context: A299042 A152806 A122109 * A297708 A284701 A011455

Adjacent sequences:  A133152 A133153 A133154 * A133156 A133157 A133158

KEYWORD

nonn

AUTHOR

Alan Griffiths, Oct 08 2007

STATUS

approved

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Last modified October 18 23:44 EDT 2021. Contains 348071 sequences. (Running on oeis4.)