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.

A246972 (n+1)^2 concatenated with n^2.

Original entry on oeis.org

10, 41, 94, 169, 2516, 3625, 4936, 6449, 8164, 10081, 121100, 144121, 169144, 196169, 225196, 256225, 289256, 324289, 361324, 400361, 441400, 484441, 529484, 576529, 625576, 676625, 729676, 784729, 841784, 900841, 961900, 1024961, 10891024, 11561089, 12251156, 12961225, 13691296
Offset: 0

Views

Author

N. J. A. Sloane, Sep 13 2014

Keywords

Crossrefs

Cf. A246973, A235497. For primes, see A104301.

Programs

  • Magma
    [10] cat [Seqint(Intseq(n^2) cat Intseq(n^2+2*n+1)): n in [1..50]]; // Vincenzo Librandi, Sep 13 2014
    
  • Mathematica
    Table[FromDigits[Join[Flatten[IntegerDigits[{(n + 1)^2, n^2}]]]], {n, 0, 50}] (* Vincenzo Librandi, Sep 13 2014 *)
    FromDigits/@(Join[IntegerDigits[#[[2]]],IntegerDigits[#[[1]]]]&/@ Partition[ Range[0,40]^2,2,1]) (* Harvey P. Dale, Apr 16 2015 *)
  • Python
    def A246972(n):
        return int(str((n+1)**2)+str(n**2)) # Chai Wah Wu, Sep 13 2014

A104242 Primes which are the concatenation of two consecutive square numbers.

Original entry on oeis.org

6481, 144169, 324361, 400441, 784841, 16001681, 23042401, 67246889, 77447921, 84648649, 92169409, 96049801, 1254412769, 1638416641, 1742417689, 1960019881, 2016420449, 4752447961, 5382454289, 5664457121, 5760058081, 6051661009
Offset: 1

Views

Author

Shyam Sunder Gupta, Apr 17 2005

Keywords

Comments

The second prime in this sequence, 144169, arises in the theory of modular forms, as observed by Hecke. On page 671 of Hecke (1937), Hecke works out the cusp forms of weight 24 and observes that the Hecke operators have eigenfunctions with Fourier coefficients in the quadratic field of discriminant 144169. Thanks to Jerrold B. Tunnell for this comment. See also the articles by Hida and Zagier. N. J. A. Sloane, Sep 13 2014

Examples

			The first term is 6481 which is a prime and is the concatenation of 64 and 81 which are two consecutive square numbers.
		

References

  • E. Hecke, Über Modulfunktionen und die Dirichletschen Reihen mit Eulerscher Produktentwicklung, Math. Annalen, 114 (1937), 1-28; Werke pp. 644-671. See page 671.

Crossrefs

A090738 gives the numbers n such that a(n) = (n^2 concatenated with (n+1)^2) is prime.
These are the primes in A246973. Cf. A104301, A246972.

Programs

  • Maple
    catn:= proc(a,b) 10^(1+ilog10(b))*a+b end proc:
    R:= NULL: count:= 0:
    for x from 2 by 2 while count < 100 do
      y:= catn(x^2,(x+1)^2);
      if isprime(y) then count:= count+1; R:= R, y; fi
    od:
    R; # Robert Israel, May 19 2020
  • Python
    from sympy import isprime
    A104242_list = []
    for n in range(1,2000):
        x = int(str(n**2)+str((n+1)**2))
        if isprime(x):
            A104242_list.append(x) # Chai Wah Wu, Sep 13 2014

A247337 a(n) = Lucas(n) concatenated with Fibonacci(n).

Original entry on oeis.org

20, 11, 31, 42, 73, 115, 188, 2913, 4721, 7634, 12355, 19989, 322144, 521233, 843377, 1364610, 2207987, 35711597, 57782584, 93494181, 151276765, 2447610946, 3960317711, 6407928657, 10368246368, 16776175025, 271443121393, 439204196418, 710647317811, 1149851514229
Offset: 0

Views

Author

Vincenzo Librandi, Sep 14 2014

Keywords

Crossrefs

Programs

  • Magma
    [20] cat [Seqint(Intseq(Fibonacci(n)) cat Intseq(Lucas(n))): n in [1..50]];
  • Mathematica
    Table[FromDigits[Join[Flatten[IntegerDigits[{LucasL[n], Fibonacci[n]}]]]], {n, 0, 50}]

A247338 a(n) = Fibonacci(n) concatenated with Lucas(n).

Original entry on oeis.org

2, 11, 13, 24, 37, 511, 818, 1329, 2147, 3476, 55123, 89199, 144322, 233521, 377843, 6101364, 9872207, 15973571, 25845778, 41819349, 676515127, 1094624476, 1771139603, 2865764079, 46368103682, 75025167761, 121393271443, 196418439204, 317811710647, 5142291149851
Offset: 0

Views

Author

Vincenzo Librandi, Sep 14 2014

Keywords

Crossrefs

Programs

  • Magma
    [Seqint(Intseq(Lucas(n)) cat Intseq(Fibonacci(n))): n in [0..50]];
    
  • Mathematica
    Table[FromDigits[Join[Flatten[IntegerDigits[{Fibonacci[n], LucasL[n]}]]]], {n, 0, 50}]
  • PARI
    a(n)=eval(Str(fibonacci(n),fibonacci(n-1)+fibonacci(n+1))) \\ Charles R Greathouse IV, Sep 14 2014
Showing 1-4 of 4 results.