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.

A305618 Expansion of e.g.f. log(1 + Sum_{k>=1} x^prime(k)/prime(k)!).

Original entry on oeis.org

0, 1, 1, -3, -9, 20, 190, -126, -6280, -10326, 293041, 1519320, -16985045, -194560444, 1013712777, 27317463952, -19210030599, -4305097718760, -17733269020226, 743855089334604, 7868686621862292, -132351392654695270, -2854492900112993039, 20150897206881256464
Offset: 1

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Author

Ilya Gutkovskiy, Jun 06 2018

Keywords

Comments

Logarithmic transform of A010051.

Examples

			E.g.f.: A(x) = x^2/2! + x^3/3! - 3*x^4/4! - 9*x^5/5! + 20*x^6/6! + ...
exp(A(x)) = 1 + x^2/2! + x^3/3! + x^5/5! + x^7/7! + ... + x^A000040(k)/A039716(k) + ...
exp(exp(A(x))-1) = 1 + x^2/2! + x^3/3! + 3*x^4/4! + 11*x^5/5! + ... + A190476(k)*x^k/k! + ...
		

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; (t-> `if`(n=0, 0, t(n)-add(a(j)*t(n-j)*
           j*binomial(n, j), j=1..n-1)/n))(i-> `if`(isprime(i), 1, 0))
        end:
    seq(a(n), n=1..25);  # Alois P. Heinz, Dec 04 2018
  • Mathematica
    nmax = 24; Rest[CoefficientList[Series[Log[1 + Sum[x^Prime[k]/Prime[k]!, {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!]
    a[n_] := a[n] = Boole[PrimeQ[n]] - Sum[k Binomial[n, k] Boole[PrimeQ[n - k]] a[k], {k, 1, n - 1}]/n; a[0] = 0; Table[a[n], {n, 24}]

A305619 Expansion of e.g.f. log(1 + Sum_{k>=1} x^prime(k)/prime(k)).

Original entry on oeis.org

0, 1, 2, -3, 4, -10, 636, -1078, -18416, -131976, 5035920, 5333592, 187347744, -4079616528, -14669908512, -140154110640, 28743506893056, -92449999037568, 2738959517576448, -52969092379214976, 34211286306178560, -16812071564735736576, 1407763084021569335808
Offset: 1

Views

Author

Ilya Gutkovskiy, Jun 06 2018

Keywords

Examples

			E.g.f.: A(x) = x^2/2! + 2*x^3/3! - 3*x^4/4! + 4*x^5/5! - 10*x^6/6! + ...
exp(A(x)) = 1 + x^2/2 + x^3/3 + x^5/5 + x^7/7 + ... + x^A000040(k)/A000040(k) + ...
exp(exp(A(x))-1) = 1 + x^2/2! + 2*x^3/3! + 3*x^4/4! + 44*x^5/5! + ... + A218002(k)*x^k/k! + ...
		

Crossrefs

Programs

  • Maple
    a:=series(log(1+add(x^ithprime(k)/ithprime(k),k=1..100)),x=0,24): seq(n!*coeff(a,x,n),n=0..23); # Paolo P. Lava, Mar 26 2019
  • Mathematica
    nmax = 23; Rest[CoefficientList[Series[Log[1 + Sum[x^Prime[k]/Prime[k], {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!]
    a[n_] := a[n] = Boole[PrimeQ[n]] (n - 1)! - Sum[k Binomial[n, k] Boole[PrimeQ[n - k]] (n - k - 1)! a[k], {k, 1, n - 1}]/n; a[0] = 0; Table[a[n], {n, 23}]

A317255 a(n) = 149836681069944461 + (n-1)*1723457117682300.

Original entry on oeis.org

149836681069944461, 151560138187626761, 153283595305309061, 155007052422991361, 156730509540673661, 158453966658355961, 160177423776038261, 161900880893720561, 163624338011402861, 165347795129085161, 167071252246767461, 168794709364449761, 170518166482132061
Offset: 1

Views

Author

Marco Ripà, Jul 25 2018

Keywords

Comments

The terms for n = 1..26 are prime. As of Jul 25 2018, this is one of the longest known sequences of primes in arithmetic progression.

Examples

			a(26) = 149836681069944461 + 25*7725290*223092870 = 192923109012001961 is prime.
		

Crossrefs

Programs

  • GAP
    List([1..25], n->149836681069944461+(n-1)*1723457117682300);
  • Maple
    seq(149836681069944461+(n-1)*1723457117682300,n=1..25);
  • Mathematica
    Table[149836681069944461 + (n - 1) 1723457117682300, {n, 1, 25}]

A317259 a(n) = 136926916457315893 + (n - 1)*9843204333812850.

Original entry on oeis.org

136926916457315893, 146770120791128743, 156613325124941593, 166456529458754443, 176299733792567293, 186142938126380143, 195986142460192993, 205829346794005843, 215672551127818693, 225515755461631543, 235358959795444393, 245202164129257243, 255045368463070093
Offset: 1

Views

Author

Marco Ripà, Jul 25 2018

Keywords

Comments

The terms for n = 1..26 are prime. As of Jul 25 2018, this is one of the longest known sequences of primes in arithmetic progression.
a(27) = 392850229136449993 = 41 * 179 * 53529122378587.
To date, an arithmetic sequence of 27 primes has not been found yet.

Examples

			a(26) = 136926916457315893 + 25*44121555*223092870 = 383007024802637143 is prime.
		

Crossrefs

Programs

  • GAP
    List([1..25], n->136926916457315893+(n-1)*9843204333812850);
  • Maple
    seq(136926916457315893+(n-1)*9843204333812850,n=1..25);
  • Mathematica
    Table[136926916457315893 + (n - 1) 9843204333812850, {n, 1, 25}]

Extensions

a(7) corrected by Georg Fischer, Mar 13 2020
Showing 1-4 of 4 results.