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.

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A017338 a(n) = (10*n + 5)^10.

Original entry on oeis.org

9765625, 576650390625, 95367431640625, 2758547353515625, 34050628916015625, 253295162119140625, 1346274334462890625, 5631351470947265625, 19687440434072265625, 59873693923837890625, 162889462677744140625, 404555773570791015625, 931322574615478515625
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Magma
    [(10*n+5)^10: n in [0..10]]; // Vincenzo Librandi, Aug 02 2011
  • Mathematica
    (10 Range[0,20]+5)^10 (* or *) LinearRecurrence[{11,-55,165,-330,462,-462,330,-165,55,-11,1},{9765625,576650390625,95367431640625,2758547353515625,34050628916015625,253295162119140625,1346274334462890625,5631351470947265625,19687440434072265625,59873693923837890625,162889462677744140625},20] (* Harvey P. Dale, Jul 18 2021 *)

Formula

G.f.: -9765625*(x^10 + 59038*x^9 + 9116141*x^8 + 178300904*x^7 + 906923282*x^6 + 1527092468*x^5 + 906923282*x^4 + 178300904*x^3 + 9116141*x^2 + 59038*x + 1)/(x-1)^11. - Colin Barker, Nov 14 2012
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^10.
a(n) = 5^10 * A016762(n).
Sum_{n>=0} 1/a(n) = 31*Pi^10/28350000000000. (End)

A267755 Expansion of (1 + 2*x + x^2 + x^3 + 4*x^4 + 2*x^5)/(1 - x - x^5 + x^6).

Original entry on oeis.org

1, 3, 4, 5, 9, 12, 14, 15, 16, 20, 23, 25, 26, 27, 31, 34, 36, 37, 38, 42, 45, 47, 48, 49, 53, 56, 58, 59, 60, 64, 67, 69, 70, 71, 75, 78, 80, 81, 82, 86, 89, 91, 92, 93, 97, 100, 102, 103, 104, 108, 111, 113, 114, 115, 119, 122, 124, 125, 126, 130, 133, 135, 136, 137
Offset: 0

Views

Author

Bruno Berselli, Jan 20 2016

Keywords

Comments

(m^k-1)/11 is a nonnegative integer when
. m is a member of this sequence and k is an odd multiple of 5 (A017329),
. m is a member of A017401 and k is odd but not multiple of 5 (A045572),
. m is a member of A175885 and k is even but not multiple of 5 (A217562),
. m is a member of A160542 and k is a positive multiple of 10 (A008592),
apart from the trivial case in which k=0.
Also, numbers that are congruent to {1, 3, 4, 5, 9} mod 11. Therefore, the product of two terms belongs to the sequence.
Union of this sequence and A267541 is A160542.
a(n) is prime for n = 1, 3, 10, 14, 17, 21, 24, 27, 30, 33, 40, 44, 47, ...

Examples

			From the linear recurrence:
(-A267541) ..., -13, -10, -8, -7, -6, -2, 1, 3, 4, 5, 9, 12, ... (A267755)
		

Crossrefs

Related sequences (see the first comment): A017401, A160542, A175885.

Programs

  • Magma
    m:=70; R:=PowerSeriesRing(Integers(), m); Coefficients(R!((1+2*x+x^2+x^3+4*x^4+2*x^5)/(1-x-x^5+x^6)));
    
  • Magma
    I:=[1,3,4,5,9,12]; [n le 6 select I[n] else Self(n-1)+Self(n-5)-Self(n-6): n in [1..70]]; // Vincenzo Librandi, Jan 21 2016
  • Maple
    gf := (1 + 2*x + x^2 + x^3 + 4*x^4 + 2*x^5)/(1 - x - x^5 + x^6): deg := 64: series(gf, x, deg): seq(coeff(%, x, n), n=0..deg-1); # Peter Luschny, Jan 21 2016
  • Mathematica
    CoefficientList[Series[(1 + 2 x + x^2 + x^3 + 4 x^4 + 2 x^5)/(1 - x - x^5 + x^6), {x, 0, 70}], x]
    LinearRecurrence[{1, 0, 0, 0, 1, -1}, {1, 3, 4, 5, 9, 12}, 70]
    Select[Range[140], MemberQ[{1, 3, 4, 5, 9}, Mod[#, 11]]&]
  • PARI
    Vec((1+2*x+x^2+x^3+4*x^4+2*x^5)/(1-x-x^5+x^6)+O(x^70))
    
  • Sage
    gf = (1 + 2*x + x^2 + x^3 + 4*x^4 + 2*x^5)/(1 - x - x^5 + x^6)
    print(taylor(gf, x, 0, 63).list()) # Peter Luschny, Jan 21 2016
    

Formula

G.f.: (1 + 2*x + x^2 + x^3 + 4*x^4 + 2*x^5)/((1 - x)^2*(1 + x + x^2 + x^3 + x^4)).
a(n) = a(n-1) + a(n-5) - a(n-6).
a(-n) = -A267541(n-1).
a(n) = n + 1 + 2*floor(n/5) + 3*floor((n+1)/5) + floor((n+4)/5). - Ridouane Oudra, Sep 06 2023

A326728 A(n, k) = n*(k - 1)*k/2 - k, square array for n >= 0 and k >= 0 read by ascending antidiagonals.

Original entry on oeis.org

0, 0, -1, 0, -1, -2, 0, -1, -1, -3, 0, -1, 0, 0, -4, 0, -1, 1, 3, 2, -5, 0, -1, 2, 6, 8, 5, -6, 0, -1, 3, 9, 14, 15, 9, -7, 0, -1, 4, 12, 20, 25, 24, 14, -8, 0, -1, 5, 15, 26, 35, 39, 35, 20, -9, 0, -1, 6, 18, 32, 45, 54, 56, 48, 27, -10
Offset: 0

Views

Author

Peter Luschny, Aug 04 2019

Keywords

Comments

A formal extension of the figurative numbers A139600 to negative n.

Examples

			[0] 0, -1, -2, -3, -4, -5, -6,  -7,  -8,  -9, -10, ... A001489
[1] 0, -1, -1,  0,  2,  5,  9,  14,  20,  27,  35, ... A080956
[2] 0, -1,  0,  3,  8, 15, 24,  35,  48,  63,  80, ... A067998
[3] 0, -1,  1,  6, 14, 25, 39,  56,  76,  99, 125, ... A095794
[4] 0, -1,  2,  9, 20, 35, 54,  77, 104, 135, 170, ... A014107
[5] 0, -1,  3, 12, 26, 45, 69,  98, 132, 171, 215, ... A326725
[6] 0, -1,  4, 15, 32, 55, 84, 119, 160, 207, 260, ... A270710
[7] 0, -1,  5, 18, 38, 65, 99, 140, 188, 243, 305, ...
		

Crossrefs

Cf. A001489 (n=0), A080956 (n=1), A067998 (n=2), A095794 (n=3), A014107 (n=4), A326725 (n=5), A270710 (n=6).
Columns include A008585, A016933, A017329.
Cf. A139600.

Programs

  • Maple
    A := (n, k) -> n*(k - 1)*k/2 - k:
    seq(seq(A(n - k, k), k=0..n), n=0..11);
  • Python
    def A326728Row(n):
        x, y = 1, 1
        yield 0
        while True:
            yield -x
            x, y = x + y - n, y - n
    for n in range(8):
        R = A326728Row(n)
    print([next(R) for _ in range(11)])

A385623 Array read by ascending antidiagonals: A(n,k) is the number obtained by concatenation of n with k in that order, with k >= 0.

Original entry on oeis.org

0, 10, 1, 20, 11, 2, 30, 21, 12, 3, 40, 31, 22, 13, 4, 50, 41, 32, 23, 14, 5, 60, 51, 42, 33, 24, 15, 6, 70, 61, 52, 43, 34, 25, 16, 7, 80, 71, 62, 53, 44, 35, 26, 17, 8, 90, 81, 72, 63, 54, 45, 36, 27, 18, 9, 100, 91, 82, 73, 64, 55, 46, 37, 28, 19, 10, 110, 101, 92, 83, 74, 65, 56, 47, 38, 29, 110, 11
Offset: 0

Views

Author

Stefano Spezia, Jul 05 2025

Keywords

Examples

			Array begins as:
   0,  1,  2,  3,  4,  5,  6,  7, ...
  10, 11, 12, 13, 14, 15, 16, 17, ...
  20, 21, 22, 23, 24, 25, 26, 27, ...
  30, 31, 32, 33, 34, 35, 36, 37, ...
  40, 41, 42, 43, 44, 45, 46, 47, ...
  50, 51, 52, 53, 54, 55, 56, 57, ...
  60, 61, 62, 63, 64, 65, 66, 67, ...
  ...
		

Crossrefs

Cf. A001477 (1st row), A020338 (main diagonal), A055642, A385624 (antidiagonal sums).

Programs

  • Mathematica
    A[n_,k_]:=FromDigits[Join[IntegerDigits[n],IntegerDigits[k]]]; Table[A[n,k],{n,0,6},{k,0,7}] (* or *)
    A[n_,k_]:=If[k==0,10n,n*10^(Floor[Log10[k]]+1)+k]; Table[A[n-k,k],{n,0,11},{k,0,n}]//Flatten
  • PARI
    T(n, k) = fromdigits(concat(digits(n), digits(k))); \\ Michel Marcus, Jul 06 2025

Formula

A(n,0) = 10*n and A(n,k) = n*10^(floor(log_10(k)) + 1) + k for k > 0.

A017331 a(n) = (10*n + 5)^3.

Original entry on oeis.org

125, 3375, 15625, 42875, 91125, 166375, 274625, 421875, 614125, 857375, 1157625, 1520875, 1953125, 2460375, 3048625, 3723875, 4492125, 5359375, 6331625, 7414875, 8615125, 9938375, 11390625, 12977875, 14706125, 16581375, 18609625, 20796875, 23149125, 25672375
Offset: 0

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Author

Keywords

Crossrefs

Programs

Formula

G.f.: 125*(x+1)*(x^2 + 22*x + 1)/(x-1)^4. - Colin Barker, Nov 14 2012
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^3.
a(n) = 5^3 * A016755(n).
Sum_{n>=0} 1/a(n) = 7*zeta(3)/1000.
Sum_{n>=0} (-1)^n/a(n) = Pi^3/4000. (End)

A017332 a(n) = (10*n + 5)^4.

Original entry on oeis.org

625, 50625, 390625, 1500625, 4100625, 9150625, 17850625, 31640625, 52200625, 81450625, 121550625, 174900625, 244140625, 332150625, 442050625, 577200625, 741200625, 937890625, 1171350625, 1445900625, 1766100625, 2136750625, 2562890625, 3049800625, 3603000625
Offset: 0

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Author

Keywords

Crossrefs

Programs

  • Magma
    [(10*n+5)^4: n in [0..35]]; // Vincenzo Librandi, Aug 02 2011
  • Mathematica
    Table[(10*n + 5)^4, {n, 0, 30}] (* Amiram Eldar, Apr 18 2023 *)
    LinearRecurrence[{5,-10,10,-5,1},{625,50625,390625,1500625,4100625},30] (* Harvey P. Dale, Aug 20 2024 *)

Formula

G.f.: -625*(x^4 + 76*x^3 + 230*x^2 + 76*x+1)/(x-1)^5. - Colin Barker, Nov 14 2012
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^4.
a(n) = 5^4 * A016756(n).
Sum_{n>=0} 1/a(n) = Pi^4/60000. (End)

A017334 a(n) = (10*n + 5)^6.

Original entry on oeis.org

15625, 11390625, 244140625, 1838265625, 8303765625, 27680640625, 75418890625, 177978515625, 377149515625, 735091890625, 1340095640625, 2313060765625, 3814697265625, 6053445140625, 9294114390625, 13867245015625, 20179187015625, 28722900390625, 40089475140625
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(10*n+5)^6: n in [0..25]]; // Vincenzo Librandi, Aug 02 2011
  • Mathematica
    (10*Range[0,20]+5)^6 (* or *) LinearRecurrence[{7,-21,35,-35,21,-7,1},{15625,11390625,244140625,1838265625,8303765625,27680640625,75418890625},20] (* Harvey P. Dale, Aug 13 2013 *)

Formula

G.f.: -15625*(x^6 + 722*x^5 + 10543*x^4 + 23548*x^3 + 10543*x^2 + 722*x + 1)/(x-1)^7. - Colin Barker, Nov 14 2012
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7); a(0)=15625, a(1)=11390625, a(2)=244140625, a(3)=1838265625, a(4)=8303765625, a(5)=27680640625, a(6)=75418890625. - Harvey P. Dale, Aug 13 2013
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^6.
a(n) = 5^6 * A016758(n).
Sum_{n>=0} 1/a(n) = Pi^6/15000000. (End)

A017335 a(n) = (10*n + 5)^7.

Original entry on oeis.org

78125, 170859375, 6103515625, 64339296875, 373669453125, 1522435234375, 4902227890625, 13348388671875, 32057708828125, 69833729609375, 140710042265625, 266001988046875, 476837158203125, 817215093984375, 1347646586640625, 2149422977421875, 3329565857578125
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(10*n+5)^7: n in [0..25]]; // Vincenzo Librandi, Aug 02 2011
  • Mathematica
    Table[(10*n + 5)^7, {n, 0, 20}] (* Amiram Eldar, Apr 18 2023 *)

Formula

G.f.: 78125*(x+1)*(x^6 + 2178*x^5 + 58479*x^4 + 201244*x^3 + 58479*x^2 + 2178*x + 1)/(x-1)^8. - Colin Barker, Nov 13 2012
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^7.
a(n) = 5^7 * A016759(n).
Sum_{n>=0} 1/a(n) = 127*zeta(7)/10000000.
Sum_{n>=0} (-1)^n/a(n) = 61*Pi^7/14400000000. (End)

A017336 a(n) = (10*n + 5)^8.

Original entry on oeis.org

390625, 2562890625, 152587890625, 2251875390625, 16815125390625, 83733937890625, 318644812890625, 1001129150390625, 2724905250390625, 6634204312890625, 14774554437890625, 30590228625390625, 59604644775390625, 110324037687890625, 195408755062890625, 333160561500390625
Offset: 0

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Author

Keywords

Crossrefs

Programs

Formula

G.f.: -((390625*(x^8 + 6552*x^7 + 331612*x^6 + 2485288*x^5 + 4675014*x^4 + 2485288*x^3 + 331612*x^2 + 6552*x + 1))/(x-1)^9). - Harvey P. Dale, Nov 02 2011
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^8.
a(n) = 5^8 * A016760(n).
Sum_{n>=0} 1/a(n) = 17*Pi^8/63000000000. (End)

A017337 a(n) = (10*n + 5)^9.

Original entry on oeis.org

1953125, 38443359375, 3814697265625, 78815638671875, 756680642578125, 4605366583984375, 20711912837890625, 75084686279296875, 231616946283203125, 630249409724609375, 1551328215978515625, 3517876291919921875, 7450580596923828125, 14893745087865234375, 28334269484119140625
Offset: 0

Views

Author

Keywords

Crossrefs

Programs

  • Magma
    [(10*n+5)^9: n in [0..15]]; // Vincenzo Librandi, Aug 02 2011
  • Mathematica
    (10*Range[0,20]+5)^9 (* or *) LinearRecurrence[{10,-45,120,-210,252,-210,120,-45,10,-1},{1953125,38443359375,3814697265625,78815638671875,756680642578125,4605366583984375,20711912837890625,75084686279296875,231616946283203125,630249409724609375},20] (* Harvey P. Dale, Jul 23 2016 *)

Formula

G.f.: 1953125*(x+1)*(x^8 + 19672*x^7 + 1736668*x^6 + 19971304*x^5 + 49441990*x^4 + 19971304*x^3 + 1736668*x^2 + 19672*x + 1)/(x-1)^10. -Colin Barker, Nov 13 2012
From Amiram Eldar, Apr 18 2023: (Start)
a(n) = A017329(n)^9.
a(n) = 5^9 * A016761(n).
Sum_{n>=0} 1/a(n) = 511*zeta(9)/1000000000.
Sum_{n>=0} (-1)^n/a(n) = 277*Pi^9/16128000000000. (End)
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