cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A168156 Sum of the binary digits of all primes between 2^(n-1) and 2^n-1, i.e., with exactly n binary digits.

Original entry on oeis.org

0, 3, 5, 6, 18, 29, 56, 113, 240, 452, 885, 1790, 3474, 6951, 13671, 27183, 54201, 107224, 213882, 424513, 845716, 1682456, 3350362, 6671581, 13299828, 26500297, 52829961, 105342821, 210088965, 419106389, 836097752, 1668341390, 3329412989, 6645128078
Offset: 1

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Author

M. F. Hasler, Nov 20 2009

Keywords

Comments

Sequence A168155 yields the partial sums.

Examples

			No prime can be written with only 1 binary digit, thus a(1)=0.
The primes that can be written with 2 binary digits are 2 = 10[2] and 3 = 11[2], they have 3 nonzero bits, so a(2)=3.
Primes with 3 binary digits are 5 = 101[2] and 7 = 111[3]. They have a total of a(3)=5 nonzero bits.
		

Crossrefs

Cf. A086904.

Programs

  • PARI
    s=0; L=p=2; while( L*=2, print1(s", "); s=0; until( L
    				
  • PARI
    a(n)=my(s); forprime(p=2^(n-1),2^n-1, s+=hammingweight(p)); s \\ Charles R Greathouse IV, Apr 07 2020

Extensions

a(26)-a(32) from Donovan Johnson, Jul 28 2010
a(33) from Chai Wah Wu, Apr 06 2020
a(34) from Chai Wah Wu, Apr 07 2020