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 1-4 of 4 results.

A286623 Square array A(n,k) = A276943(n,k)/A002110(n-1), read by descending antidiagonals A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), etc.

Original entry on oeis.org

1, 3, 1, 4, 4, 1, 5, 6, 6, 1, 7, 7, 10, 8, 1, 9, 16, 11, 14, 12, 1, 10, 19, 36, 15, 22, 14, 1, 11, 21, 41, 78, 23, 26, 18, 1, 13, 22, 45, 85, 144, 27, 34, 20, 1, 15, 31, 46, 91, 155, 222, 35, 38, 24, 1, 16, 34, 71, 92, 165, 235, 324, 39, 46, 30, 1, 17, 36, 76, 155, 166, 247, 341, 438, 47, 58, 32, 1, 18, 37, 80, 162, 287, 248, 357, 457, 668, 59, 62, 38, 1
Offset: 1

Views

Author

Antti Karttunen, Jun 28 2017

Keywords

Examples

			The top left 12 X 12 corner of the array:
  1,  3,  4,  5,    7,    9,   10,   11,   13,   15,   16,   17
  1,  4,  6,  7,   16,   19,   21,   22,   31,   34,   36,   37
  1,  6, 10, 11,   36,   41,   45,   46,   71,   76,   80,   81
  1,  8, 14, 15,   78,   85,   91,   92,  155,  162,  168,  169
  1, 12, 22, 23,  144,  155,  165,  166,  287,  298,  308,  309
  1, 14, 26, 27,  222,  235,  247,  248,  443,  456,  468,  469
  1, 18, 34, 35,  324,  341,  357,  358,  647,  664,  680,  681
  1, 20, 38, 39,  438,  457,  475,  476,  875,  894,  912,  913
  1, 24, 46, 47,  668,  691,  713,  714, 1335, 1358, 1380, 1381
  1, 30, 58, 59,  900,  929,  957,  958, 1799, 1828, 1856, 1857
  1, 32, 62, 63, 1148, 1179, 1209, 1210, 2295, 2326, 2356, 2357
  1, 38, 74, 75, 1518, 1555, 1591, 1592, 3035, 3072, 3108, 3109
		

Crossrefs

Transpose: A286625.
Row 1: A276155.
Column 1: A000012, Column 2: A008864, Column 3: A100484, Column 4: A072055, Column 5: A023523 (from its second term onward), Column 6: A286624 (= 1 + A123134), Column 11: 2*A123134, Column 13: 3*A006094.
Cf. A276616 (analogous array).

Programs

Formula

A(n,k) = A276943(n, k) / A002110(n-1).

A286624 a(n) = (prime(1+n)*prime(n)) + prime(n) + 1.

Original entry on oeis.org

9, 19, 41, 85, 155, 235, 341, 457, 691, 929, 1179, 1555, 1805, 2065, 2539, 3181, 3659, 4149, 4825, 5255, 5841, 6637, 7471, 8723, 9895, 10505, 11125, 11771, 12427, 14465, 16765, 18079, 19181, 20851, 22649, 23859, 25749, 27385, 29059, 31141, 32579, 34753, 37055, 38215, 39401, 42189, 47265, 50845, 52211
Offset: 1

Views

Author

Antti Karttunen, Jun 28 2017

Keywords

Comments

9 is the only perfect square in this sequence. - Altug Alkan, Jul 01 2017

Crossrefs

Row 6 of A286625 (column 6 of A286623). Column 4 of A328464.
One more than A123134.
Cf. A000040, A023523, A180932 (primes in this sequence).

Programs

Formula

a(n) = (A000040(1+n)*A000040(n)) + A000040(n) + 1.
a(n) = 1 + A123134(n).
a(n) = A000040(n) + A023523(1+n).

A345727 a(n) = (prime(n)+1) * prime(n+1).

Original entry on oeis.org

9, 20, 42, 88, 156, 238, 342, 460, 696, 930, 1184, 1558, 1806, 2068, 2544, 3186, 3660, 4154, 4828, 5256, 5846, 6640, 7476, 8730, 9898, 10506, 11128, 11772, 12430, 14478, 16768, 18084, 19182, 20860, 22650, 23864, 25754, 27388, 29064, 31146, 32580, 34762
Offset: 1

Views

Author

Simon Strandgaard, Jul 20 2021

Keywords

Examples

			a(1) = (prime(1)+1) * prime(2) = 3 *  3 =  9,
a(2) = (prime(2)+1) * prime(3) = 4 *  5 = 20,
a(3) = (prime(3)+1) * prime(4) = 6 *  7 = 42,
a(4) = (prime(4)+1) * prime(5) = 8 * 11 = 88.
		

Crossrefs

Programs

  • Maple
    A345727 := proc(n)
        (ithprime(n)+1)*ithprime(n+1) ;
    end proc:
    seq(A345727(n),n=1..10) ; # R. J. Mathar, Aug 16 2021
  • Mathematica
    (Prime@#+1)Prime[#+1]&/@Range@50 (* Giorgos Kalogeropoulos, Jul 23 2021 *)
    (#[[1]]+1)#[[2]]&/@Partition[Prime[Range[50]],2,1] (* Harvey P. Dale, Jan 08 2023 *)
  • PARI
    for(n=1, 100, print1((prime(n)+1)*prime(n+1), ", "))
    
  • Ruby
    require 'prime'
    values = []
    primes = Prime.first(20)
    primes.each_index do |n|
        next if n < 1
        values << (primes[n - 1] + 1) * primes[n]
    end
    p values

Formula

a(n) = A008864(n)*A000040(n+1).
a(n) = A180617(n)-A008864(n).
a(n) = A006094(n)+A000040(n+1).

A123139 a(n) = prime(n)*(prime(n + 1) + 1) - (n^3 + sum of digits of n^3).

Original entry on oeis.org

6, 2, 4, 10, 21, 9, -13, -64, -57, -73, -161, -192, -412, -697, -855, -935, -1272, -1702, -2063, -2754, -3439, -4031, -4714, -5120, -5750, -7098, -8586, -10201, -11989, -12545, -13055, -14716, -16784, -18473, -20253, -22825, -24924, -27514, -30288, -32870, -36369, -39363, -42481, -46996, -51743
Offset: 1

Views

Author

Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 30 2006

Keywords

Programs

  • Mathematica
    Table[Prime[n](Prime[n+1]+1)-(n^3+Total[IntegerDigits[n^3]]),{n,50}] (* Harvey P. Dale, Jul 03 2021 *)
  • PARI
    for(n=1,50,sda=eval(Vec(Str(n^3)));print1(prime(n)*(prime(n+1)+1)-(n^3+sum(i=1,length(sda),sda[i])),","))

Formula

a(n) = A123134(n) - A123135(n). - Michel Marcus, Dec 03 2013
Showing 1-4 of 4 results.