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 1-10 of 13 results. Next

A075110 Concatenation of n-th prime and n in decimal notation.

Original entry on oeis.org

21, 32, 53, 74, 115, 136, 177, 198, 239, 2910, 3111, 3712, 4113, 4314, 4715, 5316, 5917, 6118, 6719, 7120, 7321, 7922, 8323, 8924, 9725, 10126, 10327, 10728, 10929, 11330, 12731, 13132, 13733, 13934, 14935, 15136, 15737, 16338, 16739, 17340
Offset: 1

Views

Author

Reinhard Zumkeller, Sep 03 2002

Keywords

Crossrefs

Cf. A045532.

Programs

  • Haskell
    a075110 n = read $ show (a000040 n) ++ show n :: Integer
    -- Reinhard Zumkeller, Jul 08 2014
    
  • Magma
    [Seqint(Intseq(n) cat Intseq(NthPrime(n))): n in [1..46]]; // Vincenzo Librandi, Mar 24 2019
  • Mathematica
    Table[FromDigits[Join[IntegerDigits[Prime[n]], IntegerDigits[n]]], {n, 40}] (* Vincenzo Librandi, Mar 24 2019 *)
  • PARI
    a(n) = eval(Str(prime(n), n)); \\ Michel Marcus, Mar 24 2019
    

Formula

a(n) = A000040(n)*10^(A004216(n)+1) + n.

A138821 Concatenation of n-th Fibonacci number and n-th prime.

Original entry on oeis.org

12, 13, 25, 37, 511, 813, 1317, 2119, 3423, 5529, 8931, 14437, 23341, 37743, 61047, 98753, 159759, 258461, 418167, 676571, 1094673, 1771179, 2865783, 4636889, 7502597, 121393101, 196418103, 317811107, 514229109, 832040113, 1346269127
Offset: 1

Views

Author

Omar E. Pol, Apr 05 2008, Apr 07 2008

Keywords

Examples

			a(10)=5529 because A000045(10)=55 and A000040(10)=29.
		

Crossrefs

Programs

  • Magma
    [Seqint(Intseq(NthPrime(n)) cat Intseq(Fibonacci(n))): n in [1..50]]; // Vincenzo Librandi, Jul 24 2019
  • Maple
    f:= proc(n) local p;
      p:= ithprime(n);
      combinat:-fibonacci(n)*10^(1+ilog10(p))+p
    end proc:
    seq(f(n),n=1..100); # Robert Israel, Dec 15 2014
  • Mathematica
    With[{nn=40},FromDigits[Flatten[IntegerDigits/@#]]&/@ Thread[ {Fibonacci[ Range[nn]],Prime[Range[nn]]}]] (* Harvey P. Dale, Dec 23 2011 *)

A138822 Concatenation of n-th prime and n-th Fibonacci number.

Original entry on oeis.org

21, 31, 52, 73, 115, 138, 1713, 1921, 2334, 2955, 3189, 37144, 41233, 43377, 47610, 53987, 591597, 612584, 674181, 716765, 7310946, 7917711, 8328657, 8946368, 9775025, 101121393, 103196418, 107317811, 109514229, 113832040, 1271346269
Offset: 1

Views

Author

Omar E. Pol, Apr 05 2008

Keywords

Examples

			a(10)=2955 because A000040(10)=29 and A000045(10)=55.
		

Crossrefs

Programs

  • Magma
    [Seqint(Intseq(Fibonacci(n)) cat Intseq(NthPrime(n))): n in [1..50]]; // Vincenzo Librandi, Jul 24 2019
  • Mathematica
    With[{nn=50},FromDigits[Flatten[IntegerDigits[#]]]&/@Thread[ {Prime[ Range[ nn]],Fibonacci[Range[nn]]}]] (* Harvey P. Dale, Jul 12 2014 *)

A085451 Numbers n such that n and prime[n] together use only distinct digits.

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 9, 10, 12, 15, 16, 17, 19, 20, 21, 24, 25, 27, 28, 35, 39, 40, 45, 53, 57, 58, 60, 61, 69, 70, 72, 79, 85, 89, 90, 91, 93, 96, 98, 104, 108, 120, 124, 145, 146, 147, 150, 162, 236, 237, 253, 254, 259, 315, 316, 359, 380, 384, 390, 405, 406, 460, 461, 518
Offset: 1

Views

Author

Zak Seidov, Jul 01 2003

Keywords

Comments

There are exactly 101 such numbers in the sequence. Numbers with distinct digits in A010784. Primes with distinct digits in A029743. The case n and n^2 (exactly 22 numbers) in A059930.
A178788(A045532(a(n))) = 1. [From Reinhard Zumkeller, Jun 30 2010]

Examples

			3106 is in the sequence (and the last term) because it and prime[3106]=28549 together use all 10 distinct digits.
		

Crossrefs

Programs

  • Mathematica
    bb = {}; Do[idpn = IntegerDigits[Prime[n]]; idn = IntegerDigits[n]; If[Length[idn] + Length[idpn] == Length[Union[idn, idpn]], bb = {bb, n}], {n, 1, 100000}]; Flatten[bb]

A139114 Concatenation of n-th Fibonacci number and n.

Original entry on oeis.org

11, 12, 23, 34, 55, 86, 137, 218, 349, 5510, 8911, 14412, 23313, 37714, 61015, 98716, 159717, 258418, 418119, 676520, 1094621, 1771122, 2865723, 4636824, 7502525, 12139326, 19641827, 31781128, 51422929, 83204030, 134626931, 217830932
Offset: 1

Views

Author

Omar E. Pol, Apr 09 2008

Keywords

Crossrefs

Programs

  • Mathematica
    #[[1]]*10^IntegerLength[#[[2]]]+#[[2]]&/@Table[{Fibonacci[n],n},{n,40}] (* Harvey P. Dale, Nov 03 2016 *)

A154963 Primes p such that the concatenation of p and prime(p) is prime.

Original entry on oeis.org

2, 17, 23, 41, 61, 71, 83, 127, 227, 337, 353, 499, 503, 571, 727, 887, 911, 937, 971, 1061, 1427, 1579, 1663, 1693, 1709, 1871, 1877, 1907, 1949, 1973, 2017, 2063, 2081, 2239, 2339, 2393, 2467, 2713, 2797, 2939, 2999, 3181, 3271, 3463, 3643, 3659, 3677
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jan 18 2009

Keywords

Examples

			Concatenation of prime 2 and second prime 3 is the prime 23, hence 2 is in the sequence.
Concatenation of prime 23 and 23rd prime 83 is the prime 2383, hence 23 is in the sequence.
		

Crossrefs

Cf. A045532, A155032 (resulting primes).

Programs

  • Magma
    [ p: p in PrimesUpTo(3700) | IsPrime(StringToInteger(IntegerToString(p) cat IntegerToString(NthPrime(p)))) ];
  • Mathematica
    A154963 = Select[ Prime[ Range[ 550 ] ], PrimeQ[ FromDigits[ Join[ IntegerDigits[ # ], IntegerDigits[ Prime[ # ] ] ] ] ] & ] (* Alonso del Arte Nov 12 2009 *)

Extensions

Edited and extended beyond a(3) by Klaus Brockhaus, Jan 20 2009

A155088 Numbers n such that n and prime(n) contain prime digits only.

Original entry on oeis.org

2, 3, 55, 332, 352, 375, 733, 3573, 3575, 7235, 22222, 22223, 22322, 252323, 252335, 253777, 255225, 372755, 372772, 522532, 523255, 525737, 2275325, 2275327, 2275337, 2277333, 2277337, 3325772, 27727257, 27727277, 27727732, 27737332, 27737722, 27737723
Offset: 1

Views

Author

Juri-Stepan Gerasimov, Jan 20 2009

Keywords

Comments

Indices n such that A045532(n) is in A046034. [R. J. Mathar, May 05 2010]

Examples

			352 is in the sequence since 352 and prime(352) = 2377 use only prime digits (2, 3, 5, 7). For more examples see Links.
		

Crossrefs

Programs

  • Mathematica
    pQ[n_] := Union[IntegerDigits@n, {2,3,5,7}] == {2,3,5,7}; Select[Range[10^5], pQ@# && pQ@Prime@# &] (* Giovanni Resta, Mar 11 2013 *)
    Select[Flatten[Table[FromDigits/@Tuples[{2,3,5,7},n],{n,8}]],AllTrue[ IntegerDigits[Prime[#]],PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jun 24 2015 *)

Extensions

Corrected (332, 352, 375 inserted) by R. J. Mathar, May 05 2010
a(11)-a(34) from Giovanni Resta, Mar 11 2013

A191992 Concatenation of n and the n-th composite number.

Original entry on oeis.org

14, 26, 38, 49, 510, 612, 714, 815, 916, 1018, 1120, 1221, 1322, 1424, 1525, 1626, 1727, 1828, 1930, 2032, 2133, 2234, 2335, 2436, 2538, 2639, 2740, 2842, 2944, 3045, 3146, 3248, 3349, 3450, 3551, 3652, 3754, 3855, 3956, 4057, 4158, 4260, 4362, 4463, 4564, 4665, 4766, 4868, 4969, 5070, 5172, 5274, 5375, 5476
Offset: 1

Views

Author

Kausthub Gudipati, Jun 20 2011

Keywords

Crossrefs

Cf. A045532, the prime analog of this sequence.
Cf. A246801, primes in this sequence.

Programs

  • Mathematica
    Module[{upto=55,cmps,len},cmps=Select[Range[10*upto],CompositeQ];len= Min[ Length[ cmps],upto];#[[1]]*10^IntegerLength[#[[2]]]+#[[2]]&/@ Thread[{ Range[ len],Take[cmps,len]}]] (* Harvey P. Dale, Dec 05 2016 *)
  • PARI
    n=0;for(k=4,1e3,if(isprime(k),k++);print1(n++k", ")) \\ Charles R Greathouse IV, Jun 21 2011

A253910 Concatenation of n-th prime and n-th nonprime.

Original entry on oeis.org

21, 34, 56, 78, 119, 1310, 1712, 1914, 2315, 2916, 3118, 3720, 4121, 4322, 4724, 5325, 5926, 6127, 6728, 7130, 7332, 7933, 8334, 8935, 9736, 10138, 10339, 10740, 10942, 11344, 12745, 13146, 13748, 13949, 14950, 15151, 15752, 16354, 16755, 17356, 17957, 18158, 19160, 19362, 19763, 19964, 21165, 22366, 22768, 22969
Offset: 1

Views

Author

Omar E. Pol, Feb 06 2015

Keywords

Comments

Concatenate A000040(n) and A018252(n).

Examples

			a(5) = 119 because the 5th prime is 11 and the 5th nonprime is 9.
		

Crossrefs

Programs

  • Haskell
    import Data.Function (on)
    a253911 n = a253911_list !! (n-1)
    a253911_list = map read $
       zipWith ((++) `on` show) a018252_list a000040_list :: [Integer]
    -- Reinhard Zumkeller, Feb 09 2015
  • PARI
    nprime(n)=c=0;k=1;while(k,if(!isprime(k),c++);if(c==n,return(k));k++)
    vector(50,n,eval(concat(Str(prime(n)),Str(nprime(n))))) \\ Derek Orr, Feb 06 2015
    

A253911 Concatenation of n-th nonprime and n-th prime.

Original entry on oeis.org

12, 43, 65, 87, 911, 1013, 1217, 1419, 1523, 1629, 1831, 2037, 2141, 2243, 2447, 2553, 2659, 2761, 2867, 3071, 3273, 3379, 3483, 3589, 3697, 38101, 39103, 40107, 42109, 44113, 45127, 46131, 48137, 49139, 50149, 51151, 52157, 54163, 55167, 56173, 57179, 58181, 60191, 62193, 63197, 64199, 65211, 66223, 68227, 69229
Offset: 1

Views

Author

Omar E. Pol, Feb 06 2015

Keywords

Comments

Concatenate A018252(n) and A000040(n).

Examples

			a(5) = 911 because the 5th nonprime is 9 and the 5th prime is 11.
		

Crossrefs

Programs

  • Haskell
    import Data.Function (on)
    a253911 n = a253911_list !! (n-1)
    a253911_list = map read $
       zipWith ((++) `on` show) a018252_list a000040_list :: [Integer]
    -- Reinhard Zumkeller, Feb 09 2015
  • Mathematica
    cncat[{a_,b_}]:=FromDigits[Flatten[IntegerDigits/@{a,b}]]; Module[ {nn=100,np,len},np = Select[Range[nn],!PrimeQ[#]&];len=Length[np];cncat/@Thread[{np,Prime[Range[len]]}]] (* Harvey P. Dale, Oct 17 2020 *)
  • PARI
    nprime(n)=c=0; k=1; while(k, if(!isprime(k), c++); if(c==n, return(k)); k++)
    vector(50, n, eval(concat(Str(nprime(n)), Str(prime(n))))) \\ Derek Orr, Feb 06 2015
    
Showing 1-10 of 13 results. Next