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.

User: Dumitru Damian

Dumitru Damian's wiki page.

Dumitru Damian has authored 14 sequences. Here are the ten most recent ones:

A358559 Decimal expansion of Bi(0), where Bi is the Airy function of the second kind.

Original entry on oeis.org

6, 1, 4, 9, 2, 6, 6, 2, 7, 4, 4, 6, 0, 0, 0, 7, 3, 5, 1, 5, 0, 9, 2, 2, 3, 6, 9, 0, 9, 3, 6, 1, 3, 5, 5, 3, 5, 9, 4, 7, 2, 8, 1, 8, 8, 6, 4, 8, 5, 9, 6, 5, 0, 5, 0, 4, 0, 8, 7, 8, 7, 5, 3, 0, 1, 4, 2, 9, 6, 5, 1, 9, 3, 0, 5, 5, 2, 0, 6, 4, 0, 5, 2, 9, 3
Offset: 0

Author

Dumitru Damian, Nov 22 2022

Keywords

Examples

			0.61492662744600073515092236909361355359472818864859650504087875301429651...
		

References

  • F. W. J. Olver, Asymptotics and Special Functions, Academic Press, ISBN 978-0-12-525856-2, 1974.
  • Jerome Spanier and Keith B. Oldham, "Atlas of Functions", Hemisphere Publishing Corp., 1987, chapter 56, page 559.

Crossrefs

Cf. A284867 (Ai(0)), A284868 (Ai'(0)), this sequence (Bi(0)), A358561 (Bi'(0)), A358564(Gi(0)).

Programs

  • Mathematica
    RealDigits[AiryBi[0], 10, 120][[1]] (* Amiram Eldar, Nov 28 2022 *)
  • PARI
    airy(0)[2]
    
  • PARI
    airy(0)[1]*sqrt(3)
    
  • PARI
    3^(1/3)*gamma(1/3)/(2*Pi)
    
  • SageMath
    airy_bi(0).n(algorithm='scipy', prec=250)

Formula

Bi(0) = A284867*A002194.
Bi(0) = A358564*3.
Bi(0) = 1/(3^(1/6)*A073006).
Bi(0) = A073005/(3^(1/6)*A186706).
Bi(0) = A073005/(3^(1/6)*2*A093602).
Bi(0) = 3^(1/3)*A073005/(2*A000796).
Bi(0) = A252799/(3^(1/6)*BarnesG[5/3]).
Bi(0) = 3^(1/4)/(2^(2/9) * Pi^(1/3) * AGM(2,(sqrt(2+sqrt(3))))^(1/3)), where AGM is the arithmetic-geometric mean.

A358561 Decimal expansion of the derivative Bi'(0), where Bi is the Airy function of the second kind.

Original entry on oeis.org

4, 4, 8, 2, 8, 8, 3, 5, 7, 3, 5, 3, 8, 2, 6, 3, 5, 7, 9, 1, 4, 8, 2, 3, 7, 1, 0, 3, 9, 8, 8, 2, 8, 3, 9, 0, 8, 6, 6, 2, 2, 6, 7, 9, 9, 2, 1, 2, 2, 6, 2, 0, 6, 1, 0, 8, 2, 8, 0, 8, 7, 7, 8, 3, 7, 2, 3, 3, 0, 7, 5, 5, 0, 0, 9, 7, 8, 0, 6, 4, 7, 1, 8, 5, 0, 4
Offset: 0

Author

Dumitru Damian, Nov 22 2022

Keywords

Examples

			0.44828835735382635791482371039882839086622679921226206108280877837233075...
		

References

  • F. W. J. Olver, Asymptotics and Special Functions, Academic Press, ISBN 978-0-12-525856-2, 1974.

Crossrefs

Cf. A284867 (Ai(0)), A284868 (Ai'(0)), A358559 (Bi(0)), this sequence (Bi'(0)), A358564 (Gi(0)).

Programs

  • Mathematica
    RealDigits[AiryBi'[0], 10, 120][[1]] (* Amiram Eldar, Nov 28 2022 *)
  • PARI
    derivnum(x=0, airy(x)[2])
    
  • SageMath
    airy_bi_prime(0).n(algorithm='scipy', prec=250)

Formula

Bi'(0) = A284868*A002194.
Bi'(0) = 3*Gi'(0), where Gi' is the derivative of the inhomogeneous Airy function of the first kind.
Bi'(0) = 3^(1/6)/A073005.
Bi'(0) = A073006*3^(1/6)/A186706.
Bi'(0) = A073006*3^(1/6)/2*A093602.
Bi'(0) = 3^(2/3)*A073006/(2*A000796).
Bi'(0) = 3^(1/4)*AGM(2,(sqrt(2+sqrt(3))))^(1/3)/(2^(7/9) * Pi^(2/3)), where AGM is the arithmetic-geometric mean.

A358564 Decimal expansion of Gi(0), where Gi is the inhomogeneous Airy function of the first kind (also called Scorer function).

Original entry on oeis.org

2, 0, 4, 9, 7, 5, 5, 4, 2, 4, 8, 2, 0, 0, 0, 2, 4, 5, 0, 5, 0, 3, 0, 7, 4, 5, 6, 3, 6, 4, 5, 3, 7, 8, 5, 1, 1, 9, 8, 2, 4, 2, 7, 2, 9, 5, 4, 9, 5, 3, 2, 1, 6, 8, 3, 4, 6, 9, 5, 9, 5, 8, 4, 3, 3, 8, 0, 9, 8, 8, 3, 9, 7, 6, 8, 5, 0, 6, 8, 8, 0, 1, 7, 6, 4, 6, 2
Offset: 0

Author

Dumitru Damian, Nov 22 2022

Keywords

Examples

			0.204975542482000245050307456364537851198242729549532168346959584338098839...
		

References

  • Scorer, R. S., Numerical evaluation of integrals of the form Integral_{x=x1..x2} f(x)*e^(i*phi(x))dx and the tabulation of the function Gi(z)=(1/Pi)*Integral_{u=0..oo} sin(u*z+u^3/3) du, Quart. J. Mech. Appl. Math. 3 (1950), 107-112.

Crossrefs

Cf. A284867 (Ai(0)), A284868 (Ai'(0)), A358559 (Bi(0)), A358561 (Bi'(0)), this sequence (Gi(0)).

Programs

  • Mathematica
    First[RealDigits[N[ScorerGi[0],90]]] (* Stefano Spezia, Nov 28 2022 *)
  • PARI
    airy(0)[2]/3
    
  • PARI
    1/(3^(7/6)*gamma(2/3))
    
  • PARI
    sqrt(3)*gamma(1/3)/(3^(7/6)*2*Pi)
    
  • PARI
    1/(3^(3/4)*2^(2/9)*Pi^(1/3)*sqrtn(agm(2,(sqrt(2+sqrt(3)))),3))
    
  • SageMath
    1/(3^(7/6)*gamma(2/3)).n(algorithm='scipy', prec=250)

Formula

Gi(0) = A358559/3.
Gi(0) = A284867/A002194.
Gi(0) = Hi(0)/2, where Hi is the inhomogeneous Airy function of the second kind.
Gi(0) = 1/(3^(7/6)*A073006).
Gi(0) = A073005/(3^(7/6)*A186706).
Gi(0) = A073005/(3^(7/6)*2*A093602).
Gi(0) = A073005/(3^(4/6)*2*A000796).
Gi(0) = A252799/(3^(7/6)*BarnesG(5/3)).
Gi(0) = 1/(3^(3/4) * 2^(2/9) * Pi^(1/3) * AGM(2,(sqrt(2+sqrt(3))))^(1/3)), where AGM is the arithmetic-geometric mean.

A348763 Decimal expansion of Sum_{n>=1} ((-1)^(n+1)*n)/(n+1)^2.

Original entry on oeis.org

1, 2, 9, 3, 1, 9, 8, 5, 2, 8, 6, 4, 1, 6, 7, 9, 0, 8, 8, 1, 8, 9, 7, 5, 4, 6, 1, 8, 6, 4, 8, 3, 6, 0, 2, 6, 5, 3, 3, 9, 7, 4, 8, 1, 6, 2, 4, 3, 1, 4, 3, 9, 6, 4, 7, 4, 7, 0, 9, 9, 1, 0, 5, 1, 9, 1, 6, 1, 0, 1, 1, 3, 2, 3, 1, 9, 0, 5, 7, 2, 1, 3, 1, 0, 9
Offset: 0

Author

Dumitru Damian, Oct 31 2021

Keywords

Examples

			0.12931985286416790881897546186483602653397481624314396474709910519161011...
		

Programs

  • Mathematica
    RealDigits[Pi^2/12 - Log[2], 10, 100][[1]] (* Amiram Eldar, Nov 30 2021 *)
  • PARI
    -sumalt(n=1, (-1)^n*n/(n+1)^2) \\ Charles R Greathouse IV, Nov 01 2021
    
  • PARI
    Pi^2/12-log(2) \\ Charles R Greathouse IV, Nov 01 2021
    
  • Python
    from scipy.special import zeta
    from math import log
    int(''.join(n for n in list(str(zeta(2)/2-log(2)))[2:-2]))
    
  • Python
    int(str(sum((-1)**(n+1)*n/(n+1)**2 for n in range(1,5000000)))[2:-2])
  • SageMath
    (pi^2/12-log(2)).n(digits=100)
    

Formula

Equals Pi^2/12-log(2).
Equals Sum_{k>=2} (zeta(k)-zeta(k+1))/2^k. - Amiram Eldar, Mar 20 2022
Equals Integral_{x >= 0} x/(1 + exp(x))^2 dx = (1/2) * Integral_{x >= 0} x*(x - 2)*exp(x)/(1 + exp(x))^2 dx . - Peter Bala, Apr 26 2025

A348267 Primes of the form q^3+r^5+s^7, where q,r,s are consecutive primes.

Original entry on oeis.org

19504103, 410711297, 895293793, 19205982415663, 27139128435043, 122997897555661, 2351321783571193, 33026024797765183, 44544286011297461, 257023170905666323, 630639912549644209, 896737512757442999, 2267254920439040789, 2344105012311523369, 25786002910400593997
Offset: 1

Author

Dumitru Damian, Oct 09 2021

Keywords

Comments

Exponent values (3,5,7) given by the prime triplet of the form p,p+2,p+4.

Examples

			19504103 is a term because 5^3+7^5+11^7 = 19504103 is prime;
410711297 is a term because 11^3+13^5+17^7 = 410711297 is prime.
		

Crossrefs

Programs

  • Mathematica
    Select[(#[[1]]^3 + #[[2]]^5 + #[[3]]^7) & /@ Partition[Select[Range[1000], PrimeQ], 3, 1], PrimeQ] (* Amiram Eldar, Oct 11 2021 *)
  • Sage
    def Q3R5S7(x):
        return Primes().unrank(x)^3+Primes().unrank(x+1)^5+Primes().unrank(x+2)^7
    A348267 = [Q3R5S7(x) for x in range(0,10^3) if Q3R5S7(x) in Primes()]

A348313 Primes q such that q^3+r^5+s^7 is also prime, where q,r,s are consecutive primes.

Original entry on oeis.org

5, 11, 13, 71, 73, 97, 149, 223, 229, 283, 337, 353, 401, 409, 577, 827, 887, 1051, 1277, 1321, 1489, 1543, 1627, 1787, 1931, 2237, 2467, 2903, 3137, 3181, 3559, 3917, 4243, 4357, 4363, 4441, 4583, 4723, 4933, 5113, 5693, 5839, 5857, 6007, 6043, 6053, 6121
Offset: 1

Author

Dumitru Damian, Oct 11 2021

Keywords

Comments

Exponent values (3,5,7) given by the prime triplet of the form p, p+2, p+4.

Examples

			5 is a term because 5^3+7^5+11^7 = 19504103 is prime;
11 is a term because 11^3+13^5+17^7 = 410711297 is prime.
		

Crossrefs

Programs

  • Mathematica
    Select[Partition[Select[Range[6000], PrimeQ], 3, 1], PrimeQ[#[[1]]^3 + #[[2]]^5 + #[[3]]^7] &][[;; , 1]] (* Amiram Eldar, Oct 11 2021 *)
  • PARI
    isok(p) = if (isprime(p), my(q=nextprime(p+1), r=nextprime(q+1)); isprime(p^3+q^5+r^7)); \\ Michel Marcus, Oct 11 2021
  • Sage
    def Q(x):
        if Primes().unrank(x)^3+Primes().unrank(x+1)^5+Primes().unrank(x+2)^7 in Primes():
           return Primes().unrank(x)
    A348313 = [Q(x) for x in range(0,10^3) if Q(x)!=None]
    

A348731 Decimal expansion of Integral_{x=0..1} x*log(x)/(1+x+x^2) dx (negated).

Original entry on oeis.org

1, 5, 7, 6, 6, 0, 1, 4, 9, 1, 6, 7, 8, 3, 2, 3, 3, 0, 3, 9, 0, 5, 4, 4, 6, 7, 4, 0, 6, 9, 9, 6, 2, 2, 1, 8, 2, 2, 3, 7, 4, 9, 4, 6, 5, 4, 6, 2, 9, 5, 6, 7, 6, 9, 1, 3, 4, 1, 3, 6, 0, 4, 4, 9, 7, 3, 2, 2, 5, 6, 6, 4, 4, 7, 5, 2, 5, 7, 8, 4, 8, 8, 9, 8, 1, 0, 8, 1, 8, 1, 4, 5, 7, 1, 4, 7, 9, 7, 1, 2, 5, 7, 4, 8, 0
Offset: 0

Author

Dumitru Damian, Oct 31 2021

Keywords

Examples

			-0.15766014916783233039054467406996221822374946546295676913413604497322566...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[Integrate[x*Log[x]/(1 + x + x^2), {x, 0, 1}], 10, 100][[1]] (* Amiram Eldar, Oct 31 2021 *)
    RealDigits[Pi^2/54 - PolyGamma[1, 2/3]/9, 10, 100][[1]] (* Vaclav Kotesovec, Oct 31 2021 *)
  • PARI
    intnum(x=0, 1, x*log(x)/(1+x+x^2)) \\ Michel Marcus, Oct 31 2021
  • SageMath
    RealField(25)(numerical_integral(x*log(x)/(1+x+x^2), 0, 1)[0])
    

Formula

Equals Pi^2/54 - PolyGamma(1, 2/3)/9. - Vaclav Kotesovec, Oct 31 2021

A348693 Decimal expansion of Integral_{x=0..oo} x*exp(-x)/(exp(x)+exp(-x)-1) dx.

Original entry on oeis.org

3, 1, 1, 8, 2, 1, 1, 3, 1, 8, 6, 4, 3, 2, 6, 9, 8, 3, 2, 3, 8, 3, 2, 1, 3, 7, 7, 7, 7, 7, 0, 6, 5, 0, 6, 9, 0, 7, 0, 6, 9, 2, 4, 3, 5, 5, 4, 1, 1, 6, 4, 3, 2, 5, 5, 4, 3, 9, 8, 2, 0, 0, 8, 9, 9, 6, 8, 3, 0, 6, 6, 0, 0, 8, 8, 1, 8, 0, 1, 8, 4, 5, 9, 7, 3, 8, 0, 6, 9, 4, 6, 8, 7, 5, 3, 0, 9, 4, 4, 8, 8, 1, 7, 8, 1
Offset: 0

Author

Dumitru Damian, Oct 30 2021

Keywords

Examples

			0.3118211318643269832...
		

Crossrefs

Cf. A001620.

Programs

  • Mathematica
    RealDigits[Integrate[x*Exp[-x]/(Exp[x] + Exp[-x] - 1), {x, 0, Infinity}], 10, 105][[1]] (* Amiram Eldar, Oct 30 2021 *)
  • SageMath
    RealField(45)(numerical_integral(x*exp(-x)/(exp(x)+exp(-x)-1), 0, +Infinity)[0])

A348607 Decimal expansion of BesselJ(1,2).

Original entry on oeis.org

5, 7, 6, 7, 2, 4, 8, 0, 7, 7, 5, 6, 8, 7, 3, 3, 8, 7, 2, 0, 2, 4, 4, 8, 2, 4, 2, 2, 6, 9, 1, 3, 7, 0, 8, 6, 9, 2, 0, 3, 0, 2, 6, 8, 9, 7, 1, 9, 6, 7, 5, 4, 4, 0, 1, 2, 1, 1, 3, 9, 0, 2, 0, 7, 6, 4, 0, 8, 7, 1, 1, 6, 2, 8, 9, 6, 1, 2, 1, 8, 4, 9, 4, 8, 3, 9, 9
Offset: 0

Author

Dumitru Damian, Oct 25 2021

Keywords

Examples

			0.5767248077568733872...
		

Crossrefs

Bessel function values: A334380 (J(0,1)), A091681 (J(0,2)), A334383 (J(0,sqrt(2))), this sequence (J(1,2)), A197036 (I(0,1)), A070910 (I(0,2)), A334381 (I(0,sqrt(2))), A096789 (I(1,2)).

Programs

  • Mathematica
    RealDigits[BesselJ[1, 2], 10, 100][[1]] (* Amiram Eldar, Oct 25 2021 *)
  • PARI
    besselj(1, 2) \\ Michel Marcus, Oct 25 2021
  • Sage
    bessel_J(1, 2).n(digits=100)
    

Formula

Equals Sum_{k>=0} (-1)^k/(k!*(k+1)!).

A347114 Heptagonal pandigitals.

Original entry on oeis.org

1386470925, 1423809765, 1463095872, 1536942870, 1560837942, 1583406972, 1640538297, 1738402695, 1765403829, 1795023846, 1920538647, 2056743198, 2076149583, 2089571436, 2097384615, 2301546897, 2386051749, 2453718609, 2531869704, 2587063149, 2605431798
Offset: 1

Author

Dumitru Damian, Aug 19 2021

Keywords

Comments

There are 53 pandigital heptagonal numbers with no repeated digits, i.e., 10-digit pandigital heptagonal numbers. - Harvey P. Dale, Mar 26 2022

Crossrefs

Programs

  • Mathematica
    h[n_] := n*(5*n - 3)/2; Select[h /@ Range[33000], Length @ DeleteDuplicates @ IntegerDigits[#] == 10 &] (* Amiram Eldar, Aug 19 2021 *)
    Select[PolygonalNumber[7,Range[20234,62854]],Sort[IntegerDigits[#]] == Range[ 0,9]&] (* Harvey P. Dale, Mar 26 2022 *)
  • Sage
    A000566 = list(int(n*(5*n-3)/2) for n in range(0,1000000))
    def haspan(s): return any(len(set(s[i:i+10]))==10 for i in range(len(s)-9))
    A347114 = list(elem for elem in A000566 if haspan(str(elem)))

Formula

Intersection of A000566 (heptagonal numbers) and A171102 (infinite pandigital numbers).