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A144477 a(n) = minimal number of 0's that must be changed to 1's in the binary expansion of the n-th prime in order to make it into a palindrome. 1
1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 1, 1, 2, 1, 2, 1, 1, 1, 2, 0, 2, 2, 1, 1, 2, 1, 0, 2, 2, 0, 1, 1, 2, 2, 3, 1, 2, 1, 1, 3, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, 1, 3, 1, 0, 2, 2, 3, 1, 1, 2, 2, 2, 3, 0, 1, 3, 1, 3, 1, 2, 2, 1, 1, 2, 1, 2, 3, 1, 2, 1, 3, 1, 2, 2, 0, 2, 3, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,14

LINKS

Table of n, a(n) for n=1..100.

FORMULA

a(n) is half the Hamming distance between the binary expansion of prime(n) and its reversal.

EXAMPLE

a(5) = 1 since prime(5) = 11 = 1011_2 becomes a palindrome if we change the third bit to 0.

PROG

(PARI)

HD(p)=

{

  v=binary(p); H=0; j=#v;

  for(k=1, #v, H+=abs(v[k]-v[j]); j--);

  return(H)

};

for(n=1, 100, p=prime(n); an=HD(p)/2; print1(an, ", "))

CROSSREFS

Subsequence of A037888.

Sequence in context: A159847 A327489 A257886 * A106345 A319395 A194636

Adjacent sequences:  A144474 A144475 A144476 * A144478 A144479 A144480

KEYWORD

nonn,base

AUTHOR

Washington Bomfim, Jan 15 2011, following a suggestion from Joerg Arndt.

EXTENSIONS

Edited by N. J. A. Sloane, Apr 23 2020 at the suggestion of Harvey P. Dale

STATUS

approved

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Last modified July 31 20:20 EDT 2021. Contains 346377 sequences. (Running on oeis4.)