A023572 Exponent of 2 in prime factorization of prime(n) - 3.

1, 2, 3, 1, 1, 4, 2, 1, 2, 1, 1, 3, 2, 1, 3, 1, 6, 2, 1, 2, 4, 1, 1, 1, 2, 3, 1, 1, 2, 7, 1, 3, 1, 2, 1, 5, 2, 1, 4, 1, 2, 1, 1, 2, 4, 2, 5, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 1, 3, 1, 4, 2, 1, 1, 3, 1, 3, 1, 1, 2, 2, 1, 3, 2, 1, 1, 1, 1, 5, 1, 2, 1, 2, 3, 1, 1, 1, 2, 4, 2, 2, 3, 4, 2, 1, 1, 3

Offset

3,2

Links

Robert Israel, Table of n, a(n) for n = 3..10000

Maple

seq(padic:-ordp(ithprime(n)-3, 2), n=3..100); # Robert Israel, Aug 21 2018

Mathematica

Table[IntegerExponent[Prime[n]-3, 2], {n, 3, 100}] (* Jean-François Alcover, Jun 03 2019 *)

Prog

(PARI) twos(n) = if(n%2==1||n<1, 0, twos(n/2)+1)
A023572(n) = twos(prime(n)-3)
(PARI) a(n) = valuation(prime(n)-3, 2); \\ Michel Marcus, Aug 21 2018
(Magma) [Valuation(NthPrime(n) - 3, 2): n in [3..100]]; // Vincenzo Librandi, Aug 21 2018
(Sage) [valuation(p-3, 2) for p in primes(5, 555)] # Peter Luschny, Aug 21 2018

Crossrefs

Sequence in context: A362464 A244665 A194518 * A023570 A256989 A275214

Adjacent sequences: A023569 A023570 A023571 * A023573 A023574 A023575

Keyword

nonn

Author

Clark Kimberling

Extensions

Offset set to 3 following a suggestion of R. J. Mathar, Peter Luschny, Aug 21 2018

Status

approved