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 1-6 of 6 results.

A344182 a(n) = A344026(n) XOR A344028(n).

Original entry on oeis.org

0, 0, 0, 6, 0, 0, 5, 8, 0, 0, 0, 26, 15, 26, 18, 40, 0, 0, 0, 22, 0, 0, 63, 56, 9, 14, 31, 34, 82, 124, 119, 64, 0, 0, 0, 50, 0, 0, 45, 88, 0, 0, 0, 98, 99, 38, 234, 88, 29, 114, 29, 202, 35, 34, 136, 160, 162, 444, 406, 130, 393, 430, 452, 224, 0, 0, 0, 42, 0, 0, 97, 120, 0, 0, 0, 46, 215, 222, 130, 136, 0, 0, 0, 202
Offset: 0

Views

Author

Antti Karttunen, May 16 2021

Keywords

Crossrefs

Cf. A003415, A003714 (positions of zeros), A005940, A069359, A344026, A344028.

Programs

  • PARI
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A069359(n) = (n*sumdiv(n, d, isprime(d)/d)); \\ From A069359
    A344182(n) = { my(u=A005940(1+n)); bitxor(A003415(u),A069359(u)); };

Formula

a(n) = A344026(n) XOR A344028(n) = A003415(A005940(1+n)) XOR A069359(A005940(1+n)).

A369065 Lexicographically earliest infinite sequence such that a(i) = a(j) => A344026(i) = A344026(j) for all i, j >= 0.

Original entry on oeis.org

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

Views

Author

Antti Karttunen, Jan 16 2024

Keywords

Comments

Restricted growth sequence transform of A344026, i.e., of the arithmetic derivative (A003415) as reordered by the Doudna sequence (A005940).

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A344026(n) = A003415(A005940(1+n));
    v369065 = rgs_transform(vector(1+up_to,n,A344026(n-1)));
    A369065(n) = v369065[1+n];

A344027 Arithmetic derivative applied to prime shift array: Square array A(n,k) = A003415(A246278(n,k)), read by falling antidiagonals.

Original entry on oeis.org

1, 4, 1, 5, 6, 1, 12, 8, 10, 1, 7, 27, 12, 14, 1, 16, 10, 75, 18, 22, 1, 9, 39, 16, 147, 24, 26, 1, 32, 14, 95, 20, 363, 30, 34, 1, 21, 108, 18, 203, 28, 507, 36, 38, 1, 24, 55, 500, 24, 407, 32, 867, 42, 46, 1, 13, 51, 119, 1372, 30, 611, 40, 1083, 52, 58, 1, 44, 16, 135, 275, 5324, 36, 935, 48, 1587, 60, 62, 1
Offset: 1

Views

Author

Antti Karttunen, May 07 2021

Keywords

Comments

For each column k, A343221(2*k) gives the least n (row number) where A(n,k) < A246278(n,k).
Each column is monotonic.

Examples

			The top left corner of the array:
    k = 1   2   3     4   5     6   7       8     9    10  11      12  13    14
   2k = 2   4   6     8  10    12  14      16    18    20  22      24  26    28
------+--------------------------------------------------------------------------
  n=1 | 1,  4,  5,   12,  7,   16,  9,     32,   21,   24, 13,     44, 15,   32,
    2 | 1,  6,  8,   27, 10,   39, 14,    108,   55,   51, 16,    162, 20,   75,
    3 | 1, 10, 12,   75, 16,   95, 18,    500,  119,  135, 22,    650, 24,  155,
    4 | 1, 14, 18,  147, 20,  203, 24,   1372,  275,  231, 26,   1960, 30,  287,
    5 | 1, 22, 24,  363, 28,  407, 30,   5324,  455,  495, 34,   6050, 40,  539,
    6 | 1, 26, 30,  507, 32,  611, 36,   8788,  731,  663, 42,  10816, 44,  767,
    7 | 1, 34, 36,  867, 40,  935, 46,  19652, 1007, 1071, 48,  21386, 54, 1275,
    8 | 1, 38, 42, 1083, 48, 1235, 50,  27436, 1403, 1463, 56,  31768, 60, 1539,
    9 | 1, 46, 52, 1587, 54, 1863, 60,  48668, 2175, 1955, 64,  58190, 66, 2231,
   10 | 1, 58, 60, 2523, 66, 2639, 70,  97556, 2759, 2987, 72, 102602, 76, 3219,
   11 | 1, 62, 68, 2883, 72, 3255, 74, 119164, 3663, 3503, 78, 136462, 84, 3627,
   12 | 1, 74, 78, 4107, 80, 4403, 84, 202612, 4715, 4551, 90, 219040, 96, 4847,
etc.
		

Crossrefs

Cf. A068719 (row 1).

Programs

  • PARI
    up_to = 91;
    A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
    A246278sq(row,col) = if(1==row,2*col, my(f = factor(2*col)); for(i=1, #f~, f[i,1] = prime(primepi(f[i,1])+(row-1))); factorback(f));
    A344027sq(row,col) = A003415(A246278sq(row,col));
    A344027list(up_to) = { my(v = vector(up_to), i=0); for(a=1,oo, for(col=1,a, i++; if(i > up_to, return(v)); v[i] = A344027sq(col,(a-(col-1))))); (v); };
    v344027 = A344027list(up_to);
    A344027(n) = v344027[n];

A366801 Arithmetic derivative without its inherited divisor applied to the Doudna sequence: a(n) = A342001(A005940(1+n)).

Original entry on oeis.org

0, 1, 1, 2, 1, 5, 2, 3, 1, 7, 8, 8, 2, 7, 3, 4, 1, 9, 10, 12, 12, 31, 13, 11, 2, 9, 11, 10, 3, 9, 4, 5, 1, 13, 14, 16, 16, 41, 17, 17, 18, 59, 71, 46, 19, 41, 18, 14, 2, 11, 13, 14, 17, 37, 16, 13, 3, 11, 14, 12, 4, 11, 5, 6, 1, 15, 16, 24, 18, 61, 25, 23, 20, 87, 103, 62, 27, 55, 24, 22, 24, 113, 131, 94, 167, 247
Offset: 0

Views

Author

Antti Karttunen, Oct 24 2023

Keywords

Crossrefs

Cf. A003415, A005940, A342001, A344026, A366802 (rgs-transform).
Cf. also A342002.

Programs

A344028 a(n) = A069359(A005940(1+n)).

Original entry on oeis.org

0, 1, 1, 2, 1, 5, 3, 4, 1, 7, 8, 10, 5, 15, 9, 8, 1, 9, 10, 14, 12, 31, 24, 20, 7, 35, 40, 30, 25, 45, 27, 16, 1, 13, 14, 18, 16, 41, 30, 28, 18, 59, 71, 62, 60, 93, 72, 40, 11, 63, 70, 70, 84, 155, 120, 60, 49, 175, 200, 90, 125, 135, 81, 32, 1, 15, 16, 26, 18, 61, 42, 36, 20, 87, 103, 82, 80, 123, 90, 56, 24, 113, 131
Offset: 0

Views

Author

Antti Karttunen, May 11 2021

Keywords

Comments

Coincides with A344026 on Fibbinary numbers, A003714.

Crossrefs

Cf. A000079 (positions of ones), A003714, A005940, A069359, A344026, A344182.

Programs

Formula

a(n) = A069359(A005940(1+n)).

A369456 a(n) = A083345(A005940(1+n)), where A083345(n) = (n'/gcd(n,n')), n' means the arithmetic derivative of n (A003415), and A005940 is the Doudna-sequence.

Original entry on oeis.org

0, 1, 1, 1, 1, 5, 2, 3, 1, 7, 8, 4, 2, 7, 1, 2, 1, 9, 10, 6, 12, 31, 13, 11, 2, 9, 11, 5, 3, 3, 4, 5, 1, 13, 14, 8, 16, 41, 17, 17, 18, 59, 71, 23, 19, 41, 6, 7, 2, 11, 13, 7, 17, 37, 16, 13, 3, 11, 14, 2, 4, 11, 5, 3, 1, 15, 16, 12, 18, 61, 25, 23, 20, 87, 103, 31, 27, 55, 8, 11, 24, 113, 131, 47, 167, 247, 106, 61
Offset: 0

Views

Author

Antti Karttunen, Jan 27 2024

Keywords

Crossrefs

Cf. A005940, A083345, A369457 (rgs-transform).
Cf. also A344026, A366801.

Programs

  • PARI
    A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
    A083345(n) = { my(f=factor(n)); numerator(vecsum(vector(#f~, i, f[i, 2]/f[i, 1]))); };
    A369456(n) = A083345(A005940(1+n));

Formula

For all n > 0, a(n)|A366801(n)|A344026(n).
Showing 1-6 of 6 results.