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 1-7 of 7 results.

A276945 Square array A(row,col): A(row,1) = A276155(row), and for col > 1, A(row,col) = A276154(A(row,col-1)); Dispersion of primorial base left shift A276154.

Original entry on oeis.org

1, 2, 3, 6, 8, 4, 30, 36, 12, 5, 210, 240, 60, 14, 7, 2310, 2520, 420, 66, 32, 9, 30030, 32340, 4620, 450, 216, 38, 10, 510510, 540540, 60060, 4830, 2340, 246, 42, 11, 9699690, 10210200, 1021020, 62370, 30240, 2550, 270, 44, 13, 223092870, 232792560, 19399380, 1051050, 512820, 32550, 2730, 276, 62, 15
Offset: 1

Views

Author

Antti Karttunen, Sep 24 2016

Keywords

Comments

The array A(row,col) is read by descending antidiagonals: A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), etc.
Entries in column k are all multiples of A002110(k-1). Dividing that factor out gives array A286625. - Antti Karttunen, Jun 30 2017

Examples

			The top left corner of the array:
   1,  2,   6,   30,   210,    2310,    30030,    510510
   3,  8,  36,  240,  2520,   32340,   540540,  10210200
   4, 12,  60,  420,  4620,   60060,  1021020,  19399380
   5, 14,  66,  450,  4830,   62370,  1051050,  19909890
   7, 32, 216, 2340, 30240,  512820,  9729720, 223603380
   9, 38, 246, 2550, 32550,  542850, 10240230, 233303070
  10, 42, 270, 2730, 34650,  570570, 10720710, 242492250
  11, 44, 276, 2760, 34860,  572880, 10750740, 243002760
  13, 62, 426, 4650, 60270, 1023330, 19429410, 446696250
  15, 68, 456, 4860, 62580, 1053360, 19939920, 456395940
  16, 72, 480, 5040, 64680, 1081080, 20420400, 465585120
  17, 74, 486, 5070, 64890, 1083390, 20450430, 466095630
  18, 90, 630, 6930, 90090, 1531530, 29099070, 669278610
		

Crossrefs

Inverse permutation: A276946.
Transpose: A276943. One more than A286615.
Column 1: A276155.
Row 1: A002110.
Row 2: A276939.
Row 3: A088860 (2*A002110).
Row 11: 2*A276939 (row 2) from 16, 72, 480, 5040, 64680, ... onward.
Row 13: 3*A002110, from 18, 90, 630, 6930, 90090, ... onward.
Cf. A276154.
Cf. also arrays A286625, A276955.

Programs

Formula

A(row,1) = A276155(row); for row > 1, A(row,col) = A276154(A(row,col-1)).

A276943 Square array A(row,col) read by antidiagonals: A(1,col) = A276155(col), and for row > 1, A(row,col) = A276154(A(row-1,col)); Dispersion of primorial base left shift A276154 (array transposed).

Original entry on oeis.org

1, 3, 2, 4, 8, 6, 5, 12, 36, 30, 7, 14, 60, 240, 210, 9, 32, 66, 420, 2520, 2310, 10, 38, 216, 450, 4620, 32340, 30030, 11, 42, 246, 2340, 4830, 60060, 540540, 510510, 13, 44, 270, 2550, 30240, 62370, 1021020, 10210200, 9699690, 15, 62, 276, 2730, 32550, 512820, 1051050, 19399380, 232792560, 223092870
Offset: 1

Views

Author

Antti Karttunen, Sep 24 2016

Keywords

Comments

The array A(row,col) is read by descending antidiagonals: A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), etc.
Entries on row n are all multiples of A002110(n-1).

Examples

			The top left corner of the array:
    1,    3,    4,    5,     7,     9,    10,    11,    13,    15,    16
    2,    8,   12,   14,    32,    38,    42,    44,    62,    68,    72
    6,   36,   60,   66,   216,   246,   270,   276,   426,   456,   480
   30,  240,  420,  450,  2340,  2550,  2730,  2760,  4650,  4860,  5040
  210, 2520, 4620, 4830, 30240, 32550, 34650, 34860, 60270, 62580, 64680
		

Crossrefs

Inverse permutation: A276944.
Transpose: A276945.
Column 1: A002110, Row 1: A276155.
Cf. A276154.
Cf. also array A276953.

Programs

Formula

A(1,col) = A276155(col); for row > 1, A(row,col) = A276154(A(row-1,col)).

A276154 a(n) = Shift primorial base representation (A049345) of n left by one digit (append one zero to the right, then convert back to decimal).

Original entry on oeis.org

0, 2, 6, 8, 12, 14, 30, 32, 36, 38, 42, 44, 60, 62, 66, 68, 72, 74, 90, 92, 96, 98, 102, 104, 120, 122, 126, 128, 132, 134, 210, 212, 216, 218, 222, 224, 240, 242, 246, 248, 252, 254, 270, 272, 276, 278, 282, 284, 300, 302, 306, 308, 312, 314, 330, 332, 336, 338, 342, 344, 420, 422, 426, 428, 432, 434, 450, 452, 456, 458, 462, 464, 480, 482, 486, 488
Offset: 0

Views

Author

Antti Karttunen, Aug 24 2016

Keywords

Examples

			   n   A049345  with one zero           converted back
                appended to the right   to decimal = a(n)
---------------------------------------------------------
   0       0            00                     0
   1       1            10                     2
   2      10           100                     6
   3      11           110                     8
   4      20           200                    12
   5      21           210                    14
   6     100          1000                    30
   7     101          1010                    32
   8     110          1100                    36
   9     111          1110                    38
  10     120          1200                    42
  11     121          1210                    44
  12     200          2000                    60
  13     201          2010                    62
  14     210          2100                    66
  15     211          2110                    68
  16     220          2200                    72
		

Crossrefs

Complement: A276155.
Cf. A002110, A003961, A049345, A276085, A276086, A276151, A276152, A286629 [= a(A061720(n-1))], A324384 [= gcd(n, a(n))], A323879, A328770 (a subsequence).
Cf. also A276156, A328461, A328464.
Dispersion array and its transpose: A276943, A276945, with primorials divided out: A286623, A286625.
Analogous to A153880.

Programs

  • Mathematica
    nn = 75; b = MixedRadix[Reverse@ Prime@ NestWhileList[# + 1 &, 1, Times @@ Prime@ Range[#] <= nn &]]; Table[FromDigits[#, b] &@ Append[IntegerDigits[n, b], 0], {n, 0, nn}] (* Version 10.2, or *)
    f[n_] := Block[{a = {{0, n}}}, Do[AppendTo[a, {First@ #, Last@ #} &@ QuotientRemainder[a[[-1, -1]], Times @@ Prime@ Range[# - i]]], {i, 0, #}] &@ NestWhile[# + 1 &, 0, Times @@ Prime@ Range[# + 1] <= n &]; Rest[a][[All, 1]]]; Table[Total[Times @@@ Transpose@ {Map[Times @@ # &, Prime@ Range@ Range[0, Length@ # - 1]], Reverse@ #}] &@ Append[f@ n, 0], {n, 0, 75}] (* Michael De Vlieger, Aug 26 2016 *)
  • PARI
    A276154(n) = A276085(A003961(A276086(n))); \\ Antti Karttunen, Mar 15 2021
    
  • PARI
    A276151(n) = { my(s=1); forprime(p=2, , if(n%p, return(n-s), s *= p)); };
    A276152(n) = { my(s=1); forprime(p=2, , if(n%p, return(s*p), s *= p)); };
    A276154(n) = if(!n,n,(A276152(n) + A276154(A276151(n)))); \\ Antti Karttunen, Mar 15 2021
    
  • Scheme
    (definec (A276154 n) (if (zero? n) n (+ (A276152 n) (A276154 (A276151 n)))))

Formula

a(0) = 0; for n >= 1, a(n) = A276152(n) + a(A276151(n)).
a(n) = A276085(A003961(A276086(n))). - Antti Karttunen, Mar 15 2021

A061720 First differences of sequence of primorials.

Original entry on oeis.org

1, 4, 24, 180, 2100, 27720, 480480, 9189180, 213393180, 6246600360, 194090796900, 7220177644680, 296829525392400, 12778511068142820, 601807021256821380, 31974268694601553320, 1890171191677022594340, 115365621009252758344200, 7741033169720860084895820
Offset: 0

Views

Author

Labos Elemer, Jun 20 2001

Keywords

Comments

Largest number below primorial(n + 1) to be divisible by the first n primes. - Alonso del Arte, Dec 13 2014

Examples

			a(2) = primorial(3) - primorial(2) = 30 - 6 = 24.
a(3) = primorial(4) - primorial(3) = 210 - 30 = 180.
		

Crossrefs

Subsequence of A276155.

Programs

  • Maple
    p:= proc(n) option remember; `if`(n=0, 1, ithprime(n)*p(n-1)) end:
    a:= n-> p(n+1)-p(n):
    seq(a(n), n=0..20);  # Alois P. Heinz, Feb 23 2022
  • Mathematica
    Differences[FoldList[Times, 1, Prime[Range[20]]]] (* Alonso del Arte, Dec 13 2014 *)
  • PARI
    { n=-1; r=q=1; forprime (p=2, prime(101), r*=p; write("b061720.txt", n++, " ", r-q); q=r ) } \\ Harry J. Smith, Jul 27 2009

Formula

a(n) = A002110(n+1) - A002110(n) = A002110(n)*A006093(n+1).

Extensions

Since primorial(0) = 1, term a(0) = 1 added by Harry J. Smith, Jul 27 2009

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).

A286625 Square array A(n,k) = A276945(n,k)/A002110(k-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, 1, 3, 1, 4, 4, 1, 6, 6, 5, 1, 8, 10, 7, 7, 1, 12, 14, 11, 16, 9, 1, 14, 22, 15, 36, 19, 10, 1, 18, 26, 23, 78, 41, 21, 11, 1, 20, 34, 27, 144, 85, 45, 22, 13, 1, 24, 38, 35, 222, 155, 91, 46, 31, 15, 1, 30, 46, 39, 324, 235, 165, 92, 71, 34, 16, 1, 32, 58, 47, 438, 341, 247, 166, 155, 76, 36, 17, 1, 38, 62, 59, 668, 457, 357, 248, 287, 162, 80, 37, 18
Offset: 1

Views

Author

Antti Karttunen, Jun 28 2017

Keywords

Examples

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

Crossrefs

Transpose: A286623.
Column 1: A276155.
Row 1: A000012, Row 2: A008864, Row 3: A100484, Row 4: A072055, Row 5: A023523 (from its second term onward), Row 6: A286624.
Cf. A276617 (analogous array).

Programs

Formula

A(n,k) = A276945(n, k) / A002110(k-1).

A286630 a(0) = 1; for n >= 1, a(n) = A000040(n) * A002110(n).

Original entry on oeis.org

1, 4, 18, 150, 1470, 25410, 390390, 8678670, 184294110, 5131136010, 187621103670, 6217375194030, 274567310987970, 12474260804615610, 562558737261811290, 28899819781659096270, 1727225399291072370690, 113442860659098545705130, 7154591262923825229979470, 526507543922377892743899030, 39613798938995626228686492690
Offset: 0

Views

Author

Antti Karttunen, Jul 07 2017

Keywords

Comments

The terms a(0) .. a(5), when viewed in primorial base (A049345) look as: 1, 20, 300, 5000, 70000, E00000, where "E" stands for the digit eleven.

Crossrefs

Subsequence of A276155.

Programs

  • Mathematica
    Table[If[n==0, 1, Prime[n] Product[Prime[k], {k, n}]], {n, 0, 100}] (* Indranil Ghosh, Jul 07 2017 *)
  • PARI
    a(n) = if (n==0, 1, prime(n)*prod(k=1, n, prime(k))); \\ Michel Marcus, Jul 07 2017
  • Python
    from sympy import prime, primorial
    def a002110(n): return 1 if n<1 else primorial(n)
    def a(n): return 1 if n==0 else prime(n)*a002110(n)
    print([a(n) for n in range(41)]) # Indranil Ghosh, Jul 07 2017
    
  • Scheme
    (define (A286630 n) (if (zero? n) 1 (* (A000040 n) (A002110 n))))
    

Formula

a(0) = 1; for n >= 1, a(n) = A000040(n) * A002110(n).
For n >= 1, a(n) = A001248(n) * A002110(n-1) = A002110(n) + A286629(n).
Showing 1-7 of 7 results.