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 1-5 of 5 results.

A077665 Final term of n-th row of A077664.

Original entry on oeis.org

2, 5, 7, 11, 11, 23, 15, 23, 22, 33, 23, 47, 27, 45, 43, 47, 35, 71, 39, 69, 58, 69, 47, 95, 56, 81, 67, 93, 59, 139, 63, 95, 86, 105, 86, 143, 75, 117, 101, 139, 83, 187, 87, 139, 128, 141, 95, 191, 106, 173, 131, 163, 107, 215, 129, 185, 146, 177, 119, 283, 123, 189
Offset: 1

Views

Author

Amarnath Murthy, Nov 14 2002

Keywords

Comments

a(p) = 2p+1, p is a prime. a(2^n) = 3*2^n -1.
a(n) also equals the (n+phi(n))th integer from among those positive integers coprime to n, where phi(n) = A000010(n). a(n) also equals n + (the n-th integer from among those positive integers coprime to n) = n + A069213(n). - Leroy Quet, Apr 12 2007

Crossrefs

Programs

Extensions

More terms from Sascha Kurz, Jan 03 2003

A077666 Sum of terms of n-th row of A077664.

Original entry on oeis.org

2, 8, 16, 32, 41, 90, 78, 128, 142, 224, 188, 360, 261, 424, 436, 512, 443, 810, 552, 900, 826, 1016, 806, 1440, 1016, 1408, 1276, 1698, 1277, 2588, 1458, 2048, 1984, 2384, 2115, 3240, 2073, 2968, 2753, 3600, 2543, 4854, 2796, 4064, 3922, 4328, 3338, 5760
Offset: 1

Views

Author

Amarnath Murthy, Nov 14 2002

Keywords

Comments

a(p) = p(2p+1)- p(p+1)/2 + 1, p is a prime. a(2^n) = 2^n + (2^n)^2.

Crossrefs

Programs

Extensions

More terms from Sascha Kurz, Jan 03 2003

A260910 Triangle read by rows: Fresenius numbers of n and A077664(n,k), k = 1..n.

Original entry on oeis.org

-1, 1, 3, 5, 7, 11, 11, 17, 23, 29, 19, 23, 27, 31, 39, 29, 49, 59, 79, 89, 109, 41, 47, 53, 59, 65, 71, 83, 55, 69, 83, 97, 111, 125, 139, 153, 71, 79, 95, 103, 119, 127, 143, 151, 167, 89, 107, 143, 161, 179, 197, 233, 251, 269, 287, 109, 119, 129, 139
Offset: 1

Views

Author

Reinhard Zumkeller, Aug 04 2015

Keywords

Comments

For n > 1: T(n,1) = A028387(n-2).

Examples

			.   1:   -1
.   2:    1    3
.   3:    5    7   11
.   4:   11   17   23   29
.   5:   19   23   27   31   39
.   6:   29   49   59   79   89  109
.   7:   41   47   53   59   65   71   83
.   8:   55   69   83   97  111  125  139  153
.   9:   71   79   95  103  119  127  143  151  167
.  10:   89  107  143  161  179  197  233  251  269  287
.  11:  109  119  129  139  149  159  169  179  189  199  219
.  12:  131  175  197  241  263  307  329  373  395  439  461  505 .
		

Crossrefs

Programs

  • Haskell
    a260910 n k = a260910_tabl !! (n - 1) !! (k-1)
    a260910_row n = a260910_tabl !! (n-1)
    a260910_tabl = zipWith (map . sylvester) [1..] a077664_tabl where
       sylvester u v = u * v - u - v
  • Mathematica
    row[n_] := Module[{j, k}, Reap[For[j = n+1; k = 1, k <= n, j++, If[CoprimeQ[n, j], Sow[j]; k++]]][[2, 1]]];
    T[n_, k_] := (n-1) row[n][[k]] - n;
    Table[T[n, k], {n, 1, 12}, {k, 1, n}] // Flatten (* Jean-François Alcover, Sep 21 2021 *)

Formula

T(n,k) = (n-1) * A077664(n,k) - n.

A260895 Number of primes in n-th row of triangle A077664.

Original entry on oeis.org

1, 2, 2, 3, 2, 6, 2, 5, 4, 7, 4, 10, 3, 8, 8, 9, 4, 13, 4, 11, 8, 11, 6, 15, 7, 13, 10, 15, 7, 24, 7, 13, 12, 16, 12, 23, 9, 18, 14, 22, 10, 29, 9, 20, 17, 20, 9, 28, 12, 25, 17, 23, 12, 31, 15, 26, 18, 24, 13, 44, 12, 24, 21, 25, 18, 43, 13, 28, 21, 39, 14
Offset: 1

Views

Author

Reinhard Zumkeller, Aug 03 2015

Keywords

Comments

a(n) = sum(A010051(A077664(n,k)): k = 1..n).

Crossrefs

Programs

  • Haskell
    a260895 = sum . map a010051' . a077664_row

A077581 Triangle in which row n contains the n smallest numbers starting from 1 and coprime to n.

Original entry on oeis.org

1, 1, 3, 1, 2, 4, 1, 3, 5, 7, 1, 2, 3, 4, 6, 1, 5, 7, 11, 13, 17, 1, 2, 3, 4, 5, 6, 8, 1, 3, 5, 7, 9, 11, 13, 15, 1, 2, 4, 5, 7, 8, 10, 11, 13, 1, 3, 7, 9, 11, 13, 17, 19, 21, 23, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 1, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12
Offset: 1

Views

Author

Amarnath Murthy, Nov 14 2002

Keywords

Comments

A247815 and A247892 give number of primes and nonprimes per row. - Reinhard Zumkeller, Sep 26 2014

Examples

			1;
1,  3;
1,  2,  4;
1,  3,  5,  7;
1,  2,  3,  4,  6;
1,  5,  7, 11, 13, 17;
1,  2,  3,  4,  5,  6,  8;
1,  3,  5,  7,  9, ...
		

Crossrefs

Cf. A247798 (central terms), A247815, A247892.
Cf. A077664.

Programs

  • Haskell
    a077581 n k = a077581_tabl !! (n-1) !! (k-1)
    a077581_row n = a077581_tabl !! (n-1)
    a077581_tabl = map (\x -> take x [z | z <- [1..], gcd x z == 1]) [1..]
    -- Reinhard Zumkeller, Sep 26 2014
  • Mathematica
    row[n_] := Take[Select[Range[n^2], GCD[ #, n]==1&], n]; Join@@row/@Range[13]

Extensions

More terms from Sascha Kurz, Jan 11 2003
Showing 1-5 of 5 results.