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.

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A163917 Permutation A163915 shown in N x N grid.

Original entry on oeis.org

0, 1, 3, 7, 2, 9, 5, 6, 8, 10, 16, 4, 14, 11, 48, 17, 18, 13, 12, 51, 50, 20, 19, 28, 15, 52, 49, 60, 21, 23, 29, 31, 53, 55, 61, 63, 127, 22, 27, 30, 47, 54, 57, 62, 149, 125, 126, 25, 24, 46, 45, 59, 56, 148, 150, 118, 124, 113, 26, 39, 44, 35, 58, 152, 151, 146, 117
Offset: 0

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Author

Antti Karttunen, Sep 19 2009

Keywords

Examples

			The top left 8x8 corner of this array:
+0 +1 +7 +5 16 17 20 21
+3 +2 +6 +4 18 19 23 22
+9 +8 14 13 28 29 27 25
10 11 12 15 31 30 24 26
48 51 52 53 47 46 39 37
50 49 55 54 45 44 36 38
60 61 57 59 35 34 40 41
63 62 56 58 32 33 43 42
		

Crossrefs

Inverse: A163918. a(n) = A163915(A054238(n)) = A163355(A163907(n)) = A163905(A163357(n)). See also A163357, A163907.

A163333 Self-inverse permutation of integers: A163327-conjugate of A163332.

Original entry on oeis.org

0, 7, 2, 3, 4, 5, 6, 1, 8, 69, 64, 71, 66, 67, 68, 63, 70, 65, 18, 25, 20, 21, 22, 23, 24, 19, 26, 29, 34, 27, 32, 31, 30, 35, 28, 33, 44, 37, 42, 41, 40, 39, 38, 43, 36, 47, 52, 45, 50, 49, 48, 53, 46, 51, 54, 61, 56, 57, 58, 59, 60, 55, 62, 15, 10, 17, 12, 13, 14, 9, 16, 11
Offset: 0

Views

Author

Antti Karttunen, Jul 29 2009

Keywords

Comments

The integers [0,(9^k)-1] are confined to range [0,(9^k)-1].

Crossrefs

a(n) = A163327(A163332(A163327(n))). A163334 & A163336 give two variants of the Peano curve in an N x N grid. Cf. also A163355.

A302782 Inverse permutation to A302781.

Original entry on oeis.org

0, 1, 3, 15, 5, 2, 21, 14, 63, 6, 255, 12, 85, 20, 4, 341, 1023, 62, 4095, 10, 22, 254, 1365, 13, 5461, 86, 60, 16, 16383, 7, 65535, 340, 252, 1022, 26, 48, 21845, 4094, 84, 9, 87381, 23, 262143, 240, 58, 1366, 1048575, 342, 349525, 5460, 1020, 90, 1398101, 61, 250, 19, 4092, 16382, 4194303, 11, 16777215, 65534, 42
Offset: 1

Views

Author

Antti Karttunen, Apr 14 2018

Keywords

Crossrefs

Cf. A302781 (inverse).

Programs

  • PARI
    up_to = 8192;
    v050376 = vector(up_to);
    ispow2(n) = (n && !bitand(n,n-1));
    i = 0; for(n=1,oo,if(ispow2(isprimepower(n)), i++; v050376[i] = n); if(i == up_to,break));
    A052331(n) = { my(s=0,e); while(n > 1, fordiv(n, d, if(((n/d)>1)&&ispow2(isprimepower(n/d)), e = vecsearch(v050376, n/d); if(!e, print("v050376 too short!"); return(1/0)); s += 2^(e-1); n = d; break))); (s); };
    A006068(n)= { my(s=1, ns); while(1, ns = n >> s; if(0==ns, break()); n = bitxor(n, ns); s <<= 1; ); return (n); } \\ From A006068
    A057300(n) = { my(t=1,s=0); while(n>0, if(1==(n%4),n++,if(2==(n%4),n--)); s += (n%4)*t; n >>= 2; t <<= 2); (s); };
    A163355(n) = if(!n,n,my(i = (#binary(n)-1)\2, f = 4^i, d = (n\f)%4, r = (n%f)); if(((1==d)&&!(i%2))||((2==d)&&(i%2)), f+A163355(A057300(r)), if(3==d,f+f+A163355(A057300(r)), (3*f)+A163355(f-1-r))));
    A302845(n) = A163355(A006068(A006068(n)));
    A302782(n) = A302845(A052331(n));

Formula

a(n) = A302845(A052331(n)).
Previous Showing 21-23 of 23 results.