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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A104797 Triangle T(n,k) = Fib(n-k+4)-n-k-3, n>=1, 0<=k

Original entry on oeis.org

1, 3, 1, 7, 3, 1, 14, 7, 3, 1, 26, 14, 7, 3, 1, 46, 26, 14, 7, 3, 1, 79, 46, 26, 14, 7, 3, 1, 133, 79, 46, 26, 14, 7, 3, 1, 221, 133, 79, 46, 26, 14, 7, 3, 1, 364, 221, 133, 79, 46, 26, 14, 7, 3, 1, 596, 364, 221, 133, 79, 46, 26, 14, 7, 3, 1, 972, 596, 364, 221, 133, 79, 46, 26
Offset: 1

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Author

Gary W. Adamson, Mar 26 2005

Keywords

Comments

Repeatedly writing the sequence A001924 backwards.

Examples

			First few rows of the triangle are:
1;
3, 1;
7, 3, 1;
14, 7, 3, 1;
26, 14, 7, 3, 1;
46, 26, 14, 7, 3, 1;
...
		

Crossrefs

Row sums are in A014162.
Cf. A104732.

Extensions

Edited by Ralf Stephan, Apr 05 2009

A119997 Sum of all matrix elements of n X n matrix M[i,j] = (-1)^(i+j)*Fibonacci[i+j-1].

Original entry on oeis.org

1, 1, 4, 5, 17, 32, 97, 225, 628, 1573, 4225, 10880, 28769, 74849, 196708, 513765, 1347025, 3523360, 9229441, 24154625, 63251156, 165571781, 433507969, 1134881280, 2971250497, 7778684737, 20365103812, 53316141125, 139584105233, 365434903328, 956722661665
Offset: 1

Views

Author

Alexander Adamchuk, Aug 03 2006

Keywords

Comments

Prime p divides a(p-1) for p={5,11,19,29,31,41,59,61,71,...} = A038872[n] Primes congruent to {0, 1, 4} mod 5. Also odd primes where 5 is a square mod p. p^2 divides a(p-1) for prime p={11,19,29,31,41,59,61,71,...} = A045468[n] Primes congruent to {1, 4} mod 5. Square prime divisors of a(n) up to n=50 are{2,3,5,7,11,13,19,23,29,31,41,47,89,101,139,151,199,211,461,521,3571,9349}, It appears that square prime divisors of a(n) belong to A061446[n] Primitive part of Fibonacci(n), A001578[n] Smallest primitive prime factor of Fibonacci number F(n) and A072183[n] Sequence arising from factorization of the Fibonacci numbers. Sum[Sum[Fibonacci[i+j-1],{i,1,n}],{j,1,n}] = A120297[n]. Sum[Sum[i+j-1,{i,1,n}],{j,1,n}] = n^3. Sum[Sum[(-1)^(i+j)*(i+j-1),{i,1,n}],{j,1,n}] = n for odd n and = 0 for even n.

Examples

			Matrix begins:
1 -1 2 -3 5
-1 2 -3 5 -8
2 -3 5 -8 13
-3 5 -8 13 -21
5 -8 13 -21 34
		

Crossrefs

Programs

  • Mathematica
    Table[Sum[Sum[(-1)^(i+j)*Fibonacci[i+j-1],{i,1,n}],{j,1,n}],{n,1,50}]
  • PARI
    a(n) = sum(i=1, n, sum(j=1, n, (-1)^(i+j)*fibonacci(i+j-1))) \\ Colin Barker, Mar 26 2015
    
  • PARI
    Vec(-x*(x^3+2*x-1)/((x-1)*(x^2-3*x+1)*(x^2-x-1)) + O(x^100)) \\ Colin Barker, Mar 26 2015

Formula

a(n) = Sum[Sum[(-1)^(i+j)*Fibonacci[i+j-1],{i,1,n}],{j,1,n}].
a(n) = 3*a(n-1)+a(n-2)-7*a(n-3)+5*a(n-4)-a(n-5) for n>5. - Colin Barker, Mar 26 2015
G.f.: -x*(x^3+2*x-1) / ((x-1)*(x^2-3*x+1)*(x^2-x-1)). - Colin Barker, Mar 26 2015

A131251 A000012 * A052509.

Original entry on oeis.org

1, 2, 1, 3, 3, 1, 4, 6, 3, 1, 5, 10, 7, 3, 1, 6, 15, 14, 7, 3, 1, 7, 21, 25, 15, 7, 3, 1, 8, 28, 41, 30, 15, 7, 3, 1, 9, 36, 63, 56, 31, 15, 7, 3, 1, 10, 45, 92, 98, 62, 31, 15, 7, 3, 1
Offset: 0

Views

Author

Gary W. Adamson, Jun 23 2007

Keywords

Comments

Row sums = A001924: (1, 3, 7, 14, 26, 46, 79, ...). A131252 = A052509 * A000012.
From Clark Kimberling, Feb 07 2011: (Start)
When formatted as a rectangle R with northwest corner
1, 2, 3, 4, 5, 6, ...
1, 3, 6, 10, 15, 21, ...
1, 3, 7, 14, 25, 41, ...
1, 3, 7, 15, 30, 56, ...
1, 3, 7, 15, 31, 62, ...
...
the following properties hold:
R is the accumulation array of the transpose of A052553 (a version of Pascal's triangle); see A144112 for the definition of accumulation array.
row 1: A000027
row 2: A000217
row 3: A004006
row 4: A055795
row 5: A057703
row 6: A115567
limiting row: A000225
antidiagonal sums: A001924.
(End)

Examples

			First few rows of the triangle:
  1;
  2,  1;
  3,  3,  1;
  4,  6,  3,  1;
  5, 10,  7,  3,  1;
  6, 15, 14,  7,  3,  1;
  7, 21, 25, 15,  7,  3,  1;
  ...
		

Crossrefs

Formula

A000012 * A052509 as infinite lower triangular matrices.

A136338 Primes in the array A136431 that are not Fibonacci numbers.

Original entry on oeis.org

7, 11, 29, 37, 41, 67, 79, 97, 137, 191, 211, 277, 379, 631, 709, 821, 947, 967, 991, 1129, 1327, 1597, 1831, 2017, 2081, 2267, 2347, 2557, 2683, 2851, 2927, 3571, 3917, 4561, 4657, 4951, 5051, 5779, 6217, 6329, 6763, 8273, 8647, 8779, 9181, 9871, 10093
Offset: 1

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Author

Jonathan Vos Post, Apr 12 2008

Keywords

Comments

A generalization of prime Fibonacci numbers (A005478) are the prime hyperfibonacci numbers (primes in A136431). Referring to the array A(k,n) = Apply partial sum operator k times to Fibonacci numbers, we see that every prime occurs in the n=2 column (as it contains every positive integer).
So excluding n=2 and k=0 (A005478) we have the nontrivially prime hyperfibonacci numbers which are not Fibonacci numbers.
Note that this sequence does not indicate multiplicity (e.g., 7 occurs twice in the valid part of the table).
Continuing the table of primes in the examples, from a computation by Joshua Zucker, we have:
k=1: {7, ...} no more through n = 1000.
k=2: {7, 79, 514201, 14930317, 956722025983, 5527939700884681 4660046610375530219, ...}
k=3: {11, 97, 17519, next value has 60 digits, ...}
k=4: {41, 10093, 16703, 3520457, 591286703533, 6557470285501, 19740274219868101499, ...}
k=5: {709, 8273, 14323, 466004661037329684,1 298611126818977061133263, ...}
k=6: {29, 2683, 23945893, 1835540197, 4052735290427, 27777884012083, ...}
k=7: {37, 967, 2267, 127921, 226007, 62048869, 1131463777, 7540113804271826929, ...}
k=8: {27777538280521, 1409869790947669143312035590804646728957, ...}
k=9: {1033628323428189498226451492123369099, next value has 60 digits, ...}
k=10: {67, 5972304273877744135569337875802249660927, ...}
k=11: {79, 4478413, 19008291293, 61305228407581679, ...}
k=12: {6763, 1982269, 37886753582095837, 2791715456569622316696636389, ...}.

Examples

			k=1: primes in A000071 = {A000071(4) = 7}, no more through n = 1000.
k=2: primes in A001924 = {A001924(3) = 7, A001924(7) = 79, A001924(25) = 514201, ...}
k=3: primes in A014162 = {A014162(3) = 11, A014162(6) = 97, A014162(16) = 17519}, no more through n = 30.
k=4: primes in A014166 = {A014166(4) = 41, A014166(13) = 10093, A014166(14) = 16703}
k=5: primes in A053739 = {A053739(7) = 709, A053739(10) = 8273, A053739(11) = 14323}, no more through n = 27.
k=6: primes in A053295 = {A053295(3) = 29, A053295(8) = 2683, 23945893(24) = 23945893}, no more through n = 27.
k=7: primes in A053296 = {A053296(3) = 37, A053296(6) = 967, A053296(7) = 2267, A053296(12) = 127921, A053296(13) = 226007}, no more through n = 27.
		

Crossrefs

Programs

  • Maple
    A136431 := proc(k,n) local x ; coeftayl(x/(1-x-x^2)/(1-x)^k,x=0,n) ; end: A136338 := proc(amax) local a,k,n,a136431; a := [] ; for k from 1 do if A136431(k,3) > amax then break ; fi ; for n from 3 do a136431 := A136431(k,n) ; if a136431 > amax then break ; fi ; if isprime(a136431) and not a136431 in a then a := [op(a),a136431] ; fi ; od: od: sort(a) ; end: A136338(20000) ; # R. J. Mathar, Apr 21 2008
  • PARI
    partsumfib(N,s=[],P=[])={ for( n=1+#s,N, s=concat(s,n+1); forstep( i=n,1,-1, isprime( s[i]+= if( i>1, s[i-1], fibonacci(n+2) ) ) & P=setunion(P,[s[i]]) ); print(s); );vecsort(eval(P))} \\ M. F. Hasler

Formula

Primes in the hyperfibonacci number array of A136431, excluding the n=2 column (which contains every positive integer).

Extensions

Revised definition from N. J. A. Sloane, May 09 2008
More terms from R. J. Mathar, Apr 21 2008

A141289 Triangle read by rows, n-th row = (n-2)-th row appended to the beginning of (n-1)-th row, + n.

Original entry on oeis.org

1, 1, 2, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 4, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 4, 5, 1, 2, 1, 1, 2, 3, 4, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 4, 5, 6, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 4, 5, 1, 2, 1, 1, 2, 3, 4, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 4, 5, 6, 7
Offset: 1

Views

Author

Gary W. Adamson, Jun 22 2008

Keywords

Comments

There are (1, 2, 4, 7, 12,...) terms per row where (0, 0, 1, 2, 4, 7, 12,...) = A000071 = Fibonacci numbers - 1.
Row sums = A001924: (1, 3, 7, 14, 26, 46,...)

Examples

			First few rows of the triangle are:
1;
1, 2;
1, 1, 2, 3;
1, 2, 1, 1, 2, 3, 4;
1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 4, 5;
1, 2, 1, 1, 2, 3, 4, 1, 1, 2, 3, 1, 2, 1, 1, 2, 3, 4, 5, 6;
...
Row 4 = (1, 2, 1, 1, 2, 3, 4) = (row 2 appended to row 3, + 4); = (1, 2) appended to (1, 1, 2, 3), then 4.
		

Crossrefs

Formula

Triangle read by rows, n-th row = (n-2)-th row appended to the beginning of (n-1)-th row, + n.

A152688 Partial products of A152687.

Original entry on oeis.org

1, 1, 2, 48, 414720, 309586821120000, 62298599877271470735360000000000, 221419738218975714643056286355472083897548800000000000000000000, 30963454718960054822969246779894642673092903344400531870724683866888280945459200000000000000000000000000000000000
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Mathematica
    lst={};p0=p1=p2=p3=1;Do[p0*=a[n];p1*=p0;p2*=p1;p3*=p2;AppendTo[lst,p3],{n,1,2*3!}];lst

Extensions

Better definition from Omar E. Pol, Aug 06 2009

A210675 a(n)=a(n-1)+a(n-2)+n+4, a(0)=0, a(1)=1.

Original entry on oeis.org

0, 1, 7, 15, 30, 54, 94, 159, 265, 437, 716, 1168, 1900, 3085, 5003, 8107, 13130, 21258, 34410, 55691, 90125, 145841, 235992, 381860, 617880, 999769, 1617679, 2617479, 4235190, 6852702, 11087926, 17940663, 29028625, 46969325, 75997988, 122967352, 198965380
Offset: 0

Views

Author

Alex Ratushnyak, May 09 2012

Keywords

Crossrefs

Cf. A210673: a(n)=a(n-1)+a(n-2)+n-4, a(0)=0,a(1)=1.
Cf. A066982: a(n)=a(n-1)+a(n-2)+n-2, a(0)=0,a(1)=1 (except the first term).
Cf. A104161: a(n)=a(n-1)+a(n-2)+n-1, a(0)=0,a(1)=1.
Cf. A001924: a(n)=a(n-1)+a(n-2)+n, a(0)=0,a(1)=1.
Cf. A192760: a(n)=a(n-1)+a(n-2)+n+1, a(0)=0,a(1)=1.
Cf. A192761: a(n)=a(n-1)+a(n-2)+n+2, a(0)=0,a(1)=1.
Cf. A192762: a(n)=a(n-1)+a(n-2)+n+3, a(0)=0,a(1)=1.

Programs

Formula

a(n) = 3*a(n-1)-2*a(n-2)-a(n-3)+a(n-4). G.f.: x*(4*x^2-4*x-1) / ((x-1)^2*(x^2+x-1)). - Colin Barker, May 31 2013

A210678 a(n) = a(n-1)+a(n-2)+n+2, a(0)=a(1)=1.

Original entry on oeis.org

1, 1, 6, 12, 24, 43, 75, 127, 212, 350, 574, 937, 1525, 2477, 4018, 6512, 10548, 17079, 27647, 44747, 72416, 117186, 189626, 306837, 496489, 803353, 1299870, 2103252, 3403152, 5506435, 8909619, 14416087, 23325740, 37741862, 61067638, 98809537, 159877213, 258686789, 418564042
Offset: 0

Views

Author

Alex Ratushnyak, May 09 2012

Keywords

Crossrefs

Cf. A081659: a(n)=a(n-1)+a(n-2)+n-5, a(0)=a(1)=1 (except first 2 terms and sign).
Cf. A001924: a(n)=a(n-1)+a(n-2)+n-4, a(0)=a(1)=1 (except first 4 terms).
Cf. A000126: a(n)=a(n-1)+a(n-2)+n-2, a(0)=a(1)=1 (except first term).
Cf. A066982: a(n)=a(n-1)+a(n-2)+n-1, a(0)=a(1)=1.
Cf. A030119: a(n)=a(n-1)+a(n-2)+n, a(0)=a(1)=1.
Cf. A210677: a(n)=a(n-1)+a(n-2)+n+1, a(0)=a(1)=1.

Programs

  • Mathematica
    LinearRecurrence[{3,-2,-1,1},{1,1,6,12},40] (* Harvey P. Dale, Dec 10 2014 *)
    nxt[{n_,a_,b_}]:={n+1,b,a+b+n+3}; NestList[nxt,{1,1,1},40][[;;,2]] (* Harvey P. Dale, Mar 19 2023 *)

Formula

From Colin Barker, Jun 30 2012: (Start)
a(n) = 3*a(n-1) - 2*a(n-2) - a(n-3) + a(n-4).
G.f.: (1 -2*x + 5*x^2 - 3*x^3)/((1 - x)^2*(1 - x - x^2)). (End)

A247285 Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n (n>=1) having k (0<=k<=n-1) upper interactions.

Original entry on oeis.org

1, 1, 1, 1, 3, 1, 1, 5, 7, 1, 1, 7, 19, 14, 1, 1, 9, 36, 59, 26, 1, 1, 11, 58, 150, 162, 46, 1, 1, 13, 85, 300, 543, 408, 79, 1, 1, 15, 117, 523, 1335, 1771, 966, 133, 1, 1, 17, 154, 833, 2747, 5303, 5335, 2184, 221, 1, 1, 19, 196, 1244, 5031, 12792, 19272, 15099, 4767, 364, 1
Offset: 1

Views

Author

Emeric Deutsch, Sep 11 2014

Keywords

Comments

An upper interaction in a Dyck path is an occurrence of a string d^k u^k for some k>=1; here u = (1,1) and d = (1,-1). For example, the Dyck path uu[d(du)u]dd has 2 upper interactions, shown between parentheses.
Number of entries in row n is n.
Sum of entries in row n is the Catalan number A000108(n).
Sum(k*T(n,k), k>=0) = A172061(n-2).
The statistic "number of lower interactions", mentioned in the Le Borgne reference is basically identical with the statistic "pyramid weight" of the Denise and Simion reference (see A091866 and the bottom of p. 8 of the Le Borgne reference).
T(n+1,n) = A001924(n) for n>=1. - Alois P. Heinz, Sep 11 2014

Examples

			Row 3 is 1,3,1. Indeed, the number of upper interactions in uuuddd, uududd, uuddud, uduudd, and ududud are 0, 1, 1, 1, and 2, respectively.
Triangle starts:
1;
1,1;
1,3,1;
1,5,7,1;
1,7,19,14,1;
1,9,36,59,26,1;
		

Crossrefs

Programs

  • Maple
    q := u*t: s := ((1+t-2*q-sqrt((1-t)*(1-t-4*q+4*q^2)))*(1/2))/(t*(1-q)): Q := proc (x, n) options operator, arrow: product(1-q^k*x, k = 0 .. n-1) end proc: A := -t*add(((q-t)*s/(1-q))^n*q^(binomial(n+2, 2)-1)/(Q(q, n)*Q(q*t*s^2, n)), n = 0 .. 15)/add(((q-t)*s/(1-q))^n*q^binomial(n+2, 2)*(1-t*q^n*s)/(Q(q, n)*Q(q*t*s^2, n)*(1-q^n*s)*(1-q^(n+1)*s)), n = 0 .. 15): Aser := simplify(series(A, t = 0, 22)): for n to 16 do P[n] := sort(coeff(Aser, t, n)) end do: for n to 13 do seq(coeff(P[n], u, j), j = 0 .. n-1) end do; # yields sequence in triangular form
    # second Maple program:
    b:= proc(x, y, t, c) option remember; `if`(y<0 or y>x, 0,
         `if`(x=0, 1, expand(b(x-1, y+1, false, max(0, c-1))*
         `if`(c>0, z, 1)+b(x-1, y-1, true, 1+`if`(t, c, 0)))))
        end:
    T:= n-> (p-> seq(coeff(p, z, i), i=0..n-1))(b(2*n, 0, false, 0)):
    seq(T(n), n=1..15);  # Alois P. Heinz, Sep 11 2014
  • Mathematica
    b[x_, y_, t_, c_] := b [x, y, t, c] = If[y<0 || y>x, 0, If[x == 0, 1, Expand[b[x-1, y+1, False, Max[0, c-1]]*If[c>0, z, 1] + b[x-1, y-1, True, 1 + If[t, c, 0] ] ] ] ]; T[n_] := Function[{p}, Table[Coefficient[p, z, i], {i, 0, n-1}]][b[2*n, 0, False, 0]]; Table[T[n], {n, 1, 25}] // Flatten (* Jean-François Alcover, May 27 2015, after Alois P. Heinz *)

Formula

The g.f. A(t,u), where t marks semilength and u marks upper interactions, is given in Proposition 2 of the Le Borgne reference. It is extremely complex; the Maple program follows it (blindly), except that the infinite sums have been replaced by summations from n=0 to n=15.

A259454 Triangle T(n,k) (0 <= k <= n) read by rows, arising from the study of rook polynomials.

Original entry on oeis.org

1, 1, 3, 1, 6, 7, 1, 9, 22, 14, 1, 12, 46, 64, 26, 1, 15, 79, 177, 162, 46, 1, 18, 121, 380, 571, 374, 79, 1, 21, 172, 700, 1496, 1632, 809, 133, 1, 24, 232, 1164, 3261, 5116, 4270, 1668, 221, 1, 27, 301, 1799, 6271, 13013, 15754, 10446, 3316, 364
Offset: 0

Views

Author

N. J. A. Sloane, Jun 28 2015

Keywords

Comments

See Riordan 1954 page 18 equation (9). - Michael Somos, Aug 26 2015

Examples

			Triangle T(n,k) begins:
1;
1,  3;
1,  6,  7;
1,  9,  22,   14;
1, 12,  46,   64,   26;
1, 15,  79,  177,  162,   46;
1, 18, 121,  380,  571,  374,   79;
1, 21, 172,  700, 1496, 1632,  809,  133;
1, 24, 232, 1164, 3261, 5116, 4270, 1668, 221;
G.f. = 1 + (1 + 3*t)*u + (1 + 6*t + 7*t^2)*u^2 + ...
		

Crossrefs

Some diagonals: A001924, A001925, A001926.

Programs

  • Maple
    T:= proc(n, k) option remember; `if`(k<0 or k>n, 0,
          T(n-1, k) +2*T(n-1, k-1) +T(n-2, k-1)
         -T(n-3, k-3) +`if`(n=k, 1, 0))
        end:
    seq(seq(T(n, k), k=0..n), n=0..10);  # Alois P. Heinz, Jul 02 2015
  • Mathematica
    T[n_, k_] /; 0 <= k <= n := T[n, k] = T[n-1, k] + 2*T[n-1, k-1] + T[n-2, k - 1] - T[n-3, k-3] + Boole[n == k]; T[, ] = 0; Table[T[n, k], {n, 0, 10}, {k, 0, n}] // Flatten (* Jean-François Alcover, Feb 18 2016 *)
  • PARI
    {T(n, k) = polcoeff( polcoeff( 1 / ((1 - y*x) * (1 - (1 + 2*y)*x - y*x^2 + y^3*x^3)) + x * O(x^n), n), k)}; /* Michael Somos, Aug 26 2015 */

Formula

From Eq. (11) of Riordan (1954): T(n,k) = T(n-1,k) + 2*T(n-1,k-1) + T(n-2,k-1) - T(n-3,k-3) + delta(n,k), where delta(n,k)=1 iff n=k, otherwise 0.
Sum_{n, k} T(n, k) * x^n*y^k = 1 / ((1 - y*x) * (1 - (1 + 2*y)*x - y*x^2 + y^3*x^3)). - Michael Somos, Aug 26 2015

Extensions

More terms from Alois P. Heinz, Jul 02 2015
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