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.

Showing 1-10 of 17 results. Next

A001025 Powers of 16: a(n) = 16^n.

Original entry on oeis.org

1, 16, 256, 4096, 65536, 1048576, 16777216, 268435456, 4294967296, 68719476736, 1099511627776, 17592186044416, 281474976710656, 4503599627370496, 72057594037927936, 1152921504606846976, 18446744073709551616, 295147905179352825856, 4722366482869645213696, 75557863725914323419136, 1208925819614629174706176
Offset: 0

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Author

Keywords

Comments

Same as Pisot sequences E(1, 16), L(1, 16), P(1, 16), T(1, 16). Essentially same as Pisot sequences E(16, 256), L(16, 256), P(16, 256), T(16, 256). See A008776 for definitions of Pisot sequences.
Convolution-square (auto-convolution) of A098430. - R. J. Mathar, May 22 2009
Subsequence of A161441: A160700(a(n)) = 1. - Reinhard Zumkeller, Jun 10 2009
The compositions of n in which each natural number is colored by one of p different colors are called p-colored compositions of n. For n >= 1, a(n) equals the number of 16-colored compositions of n such that no adjacent parts have the same color. - Milan Janjic, Nov 17 2011

References

  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Partial sums give A131865.

Programs

Formula

G.f.: 1/(1-16*x).
E.g.f.: exp(16*x).
From Muniru A Asiru, Nov 07 2018: (Start)
a(n) = 16^n.
a(0) = 1, a(n) = 16*a(n-1). (End)
a(n) = 4^A005843(n) = 2^A008586(n) = A000302(n)^2 = A000079(n)*A001018(n). - Muniru A Asiru, Nov 10 2018
a(n) = ( Sum_{k = 0..n} (2*k + 1)*binomial(2*n + 1, n - k) ) * ( Sum_{k = 0..n} (-1)^k/(2*k + 1)*binomial(2*n + 1, n - k) ). - Peter Bala, Feb 12 2019
a(n) = Sum_{k = 0..2*n} A000984(k) * A000984(2*n-k). - Peter Bala, Aug 23 2025

A160700 a(n) = if n<16 then n else a(floor(n/16)) XOR (n mod 16).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 1, 0, 3, 2, 5, 4, 7, 6, 9, 8, 11, 10, 13, 12, 15, 14, 2, 3, 0, 1, 6, 7, 4, 5, 10, 11, 8, 9, 14, 15, 12, 13, 3, 2, 1, 0, 7, 6, 5, 4, 11, 10, 9, 8, 15, 14, 13, 12, 4, 5, 6, 7, 0, 1, 2, 3, 12, 13, 14, 15, 8, 9, 10, 11, 5, 4, 7, 6, 1, 0, 3, 2, 13
Offset: 0

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Author

Reinhard Zumkeller, Jun 01 2009

Keywords

Comments

A very simple hash function for the nonnegative integers.
a(A000079(n))=A133145(n); a(A000302(n))=A010685(n); a(A001025(n))=A161452(n); a(A161440(n))=0; a(A161441(n))=1; a(A161442(n))=2; a(A161443(n))=3; a(A161444(n))=4; a(A161445(n))=5; a(A161446(n))=6; a(A161447(n))=7; a(A161448(n))=8; a(A161449(n))=9; a(A161450(n))=10; a(A161451(n))=11; a(A161452(n))=12; a(A161453(n))=13; a(A161454(n))=14; a(A161455(n))=15. - Reinhard Zumkeller, Jun 10 2009

Programs

  • Haskell
    import Data.Bits (xor)
    a160700 n = a160700_list !! n
    a160700_list = [0..15] ++ map f [16..] where
       f x = a160700 x' `xor` m :: Int where (x', m) = divMod x 16
    -- Reinhard Zumkeller, Nov 07 2012
    
  • Maple
    read("transforms") ;
    A160700 := proc(n)
        if n < 16 then
            n;
        else
            XORnos(procname(floor(n/16)),modp(n,16))
        end if;
    end proc: # R. J. Mathar, Jul 12 2016
  • Mathematica
    a[n_] := a[n] = If[n < 16, n, a[Floor[n/16]] ~BitXor~ Mod[n, 16]];
    Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Jan 25 2018 *)
  • Maxima
    load(functs)$
    A160700(n):=if n<16 then n else logxor(floor(n/16),mod(n,16))$
    makelist(A160700(n),n,0,60); /* Martin Ettl, Nov 05 2012 */
    
  • PARI
    a(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t \\ Charles R Greathouse IV, Jan 25 2018

A161447 Numbers n such that A160700(n) = 7.

Original entry on oeis.org

7, 22, 37, 52, 67, 82, 97, 112, 143, 158, 173, 188, 203, 218, 233, 248, 262, 279, 292, 309, 322, 339, 352, 369, 398, 415, 428, 445, 458, 475, 488, 505, 517, 532, 551, 566, 577, 592, 611, 626, 653, 668, 687, 702, 713, 728, 747, 762, 772, 789, 806, 823, 832
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16, 16*n-1, if(a(k)==7, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018

A161440 Numbers m such that A160700(m) = 0.

Original entry on oeis.org

0, 17, 34, 51, 68, 85, 102, 119, 136, 153, 170, 187, 204, 221, 238, 255, 257, 272, 291, 306, 325, 340, 359, 374, 393, 408, 427, 442, 461, 476, 495, 510, 514, 531, 544, 561, 582, 599, 612, 629, 650, 667, 680, 697, 718, 735, 748, 765, 771, 786, 801, 816, 839
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • Mathematica
    b[n_] := b[n] = If[n < 16, n, b[Floor[n/16]]~BitXor~Mod[n, 16]];
    Select[Range[0, 1000], b[#] == 0&] (* Jean-François Alcover, Dec 01 2021 *)
  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16,16*n-1, if(a(k)==0, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018

A161442 Numbers n such that A160700(n) = 2.

Original entry on oeis.org

2, 19, 32, 49, 70, 87, 100, 117, 138, 155, 168, 185, 206, 223, 236, 253, 259, 274, 289, 304, 327, 342, 357, 372, 395, 410, 425, 440, 463, 478, 493, 508, 512, 529, 546, 563, 580, 597, 614, 631, 648, 665, 682, 699, 716, 733, 750, 767, 769, 784, 803, 818, 837
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16,16*n-1, if(a(k)==2, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018

A161443 Numbers m such that A160700(m) = 3.

Original entry on oeis.org

3, 18, 33, 48, 71, 86, 101, 116, 139, 154, 169, 184, 207, 222, 237, 252, 258, 275, 288, 305, 326, 343, 356, 373, 394, 411, 424, 441, 462, 479, 492, 509, 513, 528, 547, 562, 581, 596, 615, 630, 649, 664, 683, 698, 717, 732, 751, 766, 768, 785, 802, 819, 836
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16, 16*n-1, if(a(k)==3, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018

A161444 Numbers n such that A160700(n) = 4.

Original entry on oeis.org

4, 21, 38, 55, 64, 81, 98, 115, 140, 157, 174, 191, 200, 217, 234, 251, 261, 276, 295, 310, 321, 336, 355, 370, 397, 412, 431, 446, 457, 472, 491, 506, 518, 535, 548, 565, 578, 595, 608, 625, 654, 671, 684, 701, 714, 731, 744, 761, 775, 790, 805, 820, 835
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16, 16*n-1, if(a(k)==4, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018

A161445 Numbers n such that A160700(n) = 5.

Original entry on oeis.org

5, 20, 39, 54, 65, 80, 99, 114, 141, 156, 175, 190, 201, 216, 235, 250, 260, 277, 294, 311, 320, 337, 354, 371, 396, 413, 430, 447, 456, 473, 490, 507, 519, 534, 549, 564, 579, 594, 609, 624, 655, 670, 685, 700, 715, 730, 745, 760, 774, 791, 804, 821, 834
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16, 16*n-1, if(a(k)==5, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018

A161446 Numbers n such that A160700(n) = 6.

Original entry on oeis.org

6, 23, 36, 53, 66, 83, 96, 113, 142, 159, 172, 189, 202, 219, 232, 249, 263, 278, 293, 308, 323, 338, 353, 368, 399, 414, 429, 444, 459, 474, 489, 504, 516, 533, 550, 567, 576, 593, 610, 627, 652, 669, 686, 703, 712, 729, 746, 763, 773, 788, 807, 822, 833
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16, 16*n-1, if(a(k)==6, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018

A161448 Numbers n such that A160700(n) = 8.

Original entry on oeis.org

8, 25, 42, 59, 76, 93, 110, 127, 128, 145, 162, 179, 196, 213, 230, 247, 265, 280, 299, 314, 333, 348, 367, 382, 385, 400, 419, 434, 453, 468, 487, 502, 522, 539, 552, 569, 590, 607, 620, 637, 642, 659, 672, 689, 710, 727, 740, 757, 779, 794, 809, 824, 847
Offset: 1

Views

Author

Reinhard Zumkeller, Jun 10 2009

Keywords

Crossrefs

Programs

  • PARI
    A160700(n)=my(t=n%16); while(n>15, n>>=4; t=bitxor(t, n%16)); t
    a(n)=for(k=16*n-16, 16*n-1, if(a(k)==8, return(k))) \\ Charles R Greathouse IV, Jan 25 2018

Formula

16n - 16 <= a(n) <= 16n - 1. - Charles R Greathouse IV, Jan 25 2018
Showing 1-10 of 17 results. Next