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 22 results. Next

A069487 Areas of Pythagorean triangles (A069482, A069484, A069486).

Original entry on oeis.org

30, 240, 840, 5544, 6864, 26520, 23256, 73416, 208104, 107880, 467976, 473304, 296184, 727560, 1494600, 2101344, 863760, 3138816, 2625864, 1492704, 5259504, 4248936, 7623384, 12845904, 7759224, 4244424
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 29 2002

Keywords

Examples

			prime(2)^3 * prime(1) - prime(1)^3 * prime(2) = 3^3 * 2 - 2^3 * 3 = 54 - 24 = 30 that is the area of the Pythagorean triangle (5, 12, 13), so a(1) = 30. - _Bernard Schott_, Sep 23 2019
		

Crossrefs

Programs

  • Magma
    [NthPrime(n+1)^3*NthPrime(n)-NthPrime(n+1)*(NthPrime(n)^3):n in [1..26]]; // Marius A. Burtea, Sep 19 2019

Formula

a(n) = A030078(n+1)*A000040(n) - A000040(n+1)*A030078(n).
a(n) = A000040(n+1)^3*A000040(n) - A000040(n+1)*A000040(n)^3.
a(n) = A000040(n)*A127917(n+1) - A127917(n)*A000040(n+1). - César Aguilera, Sep 18 2019

A133529 Sum of squares of three consecutive primes.

Original entry on oeis.org

38, 83, 195, 339, 579, 819, 1179, 1731, 2331, 3171, 4011, 4899, 5739, 6867, 8499, 10011, 11691, 13251, 14859, 16611, 18459, 21051, 24219, 27531, 30219, 32259, 33939, 36099, 40779, 46059, 52059, 55251, 60291, 64323, 69651, 74019, 79107, 84387, 89859, 94731, 101283
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Comments

It is easy to see that all terms > 83 are divisible by 3.
Likewise all terms except 38 are congruent to 3 (mod 8). - Franklin T. Adams-Watters, Jun 17 2015

Examples

			a(1)=38 because 2^2 + 3^2 + 5^2 = 38.
		

Crossrefs

Programs

  • Magma
    [&+[ NthPrime(n+i)^2 :  i in [0..2]] : n in [1..20]]; // K. D. Bajpai, Jun 17 2015
  • Mathematica
    a = 2; Table[Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a, {n, 1, 100}]
    Total/@Partition[Prime[Range[50]]^2, 3, 1] (* Vincenzo Librandi, Jun 18 2015 *)
  • PARI
    for( n= 1, 100,  k= sum(i=n, n+2, prime(i)^2) ; print1(k, ", ")) \\ K. D. Bajpai, Jun 17 2015
    

Formula

a(n) = A069484(n) + A001248(n+2). - Michel Marcus, Nov 08 2013

Extensions

a(38)-a(41) from K. D. Bajpai, Jun 18 2015

A069482 a(n) = prime(n+1)^2 - prime(n)^2.

Original entry on oeis.org

5, 16, 24, 72, 48, 120, 72, 168, 312, 120, 408, 312, 168, 360, 600, 672, 240, 768, 552, 288, 912, 648, 1032, 1488, 792, 408, 840, 432, 888, 3360, 1032, 1608, 552, 2880, 600, 1848, 1920, 1320, 2040, 2112, 720, 3720, 768, 1560, 792, 4920, 5208, 1800, 912, 1848
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 29 2002, Aug 05 2007

Keywords

Comments

a(n) = A001248(n+1) - A001248(n) = A000040(n+1)^2 - A000040(n)^2 = (A000040(n+1) - A000040(n))*(A000040(n+1) + A000040(n)) = A001223(n)*A001043(n); together with A069484(n) and A069486(n) a Pythagorean triangle is formed with area = A069487(n).
For n>2: A078701(a(n)) = 3.
Except for the first two terms, these numbers are divisible by 24. Let p, q be consecutive primes. Then p > 3 = 3k+-1 and q = 3m+-1 and (3k+-1)^2 - (3m+-1)^2 is divisible by 3. Similarly, p = 4k+-1 and q=4m+-1 and (4k+-1)^2 - (4m+-1)^2 is divisible by 8. So 8 and 3 divide q^2 - p^2 => 24 divides q^2 - p^2. - Cino Hilliard, May 28 2009
Repetition of a(n) values occurs with decreasing frequency but increasing tallies (i.e., number of repetitions of a given value).
Tally = 2, first a(n) value is 72, with first n=4, prime=7.
Tally = 3, first a(n) value is 1848, with first n=36, prime=151.
Tally = 4, first a(n) value is 4920, with first n=46, prime=199.
Tally = 5, first a(n) value is 187117320, with first n=224752, prime 3118607.
Three a(n) values have a tally = 5, and none with tally > 5 for n<10,000,000. Note: Tallies for a given a(n) value are "confirmed" (i.e., not to be greater) only after examining a(n) values for all p(n) <= r/4-1, where r is the a(n) value in question, because twin primes provide the last chance for adding to the tally of any a(n) value. Tallies for the four a(n) values above are "confirmed" and all of them rely on twin primes for their last repetition. Thus r/4 +-1 is prime for the above four cases. However this is not true for all a(n) values that repeat.
Conjecture: The sum of prime factors with repetition (sopfr) applied to a(n), A001414(a(n)), covers all integers covered by sopfr, except 2,3,4,6,7,10,13,15. See A001414 for the sopfr sequence, which does not cover 0 and 1. - Richard R. Forberg, Feb 07 2015
Conjecture: There is no upper bound on the number of repetitions (i.e., size of a tally) that will occur for some a(n) values, because the number of possible ways of producing a value of a(n) grows with increasing n, despite decreasing prime density. This happens because there is increasing range in the size of prime gaps which increases the range of primes that can produce the same a(n) value much faster than the decrease in prime density which is decelerating with larger n. - Richard R. Forberg, Feb 17 2015

Examples

			A000040(10)=29, A000040(10+1)=31, A001248(10)=841, A001248(10+1)=961, a(10) = 961 - 841 = 120, A069486(10) = 2*31*29 = 1798, A069484(10) = 961 + 841 = 1802:
120^2 + 1798^2 = 14400 + 3232804 = 3247204 = 1802^2.
		

Crossrefs

Programs

  • Haskell
    a069482 n = a069482_list !! (n-1)
    a069482_list = zipWith (-) (tail a001248_list) a001248_list
    -- Reinhard Zumkeller, Jun 08 2015
    
  • Magma
    [NthPrime(n+1)^2 - NthPrime(n)^2: n in [1..40]]; // G. C. Greubel, May 19 2019
    
  • Mathematica
    Table[Prime[n+1]^2 - Prime[n]^2, {n, 1, 40}] (* Vladimir Joseph Stephan Orlovsky, Mar 01 2009; modified by G. C. Greubel, May 19 2019 *)
    #[[2]]-#[[1]]&/@Partition[Prime[Range[60]]^2,2,1] (* Harvey P. Dale, Jan 13 2011 *)
    Differences[Prime[Range[100]]^2](* Waldemar Puszkarz, Feb 09 2015 *)
  • PARI
    {a(n) = prime(n+1)^2 - prime(n)^2}; \\ G. C. Greubel, May 19 2019
    
  • Python
    from sympy import prime, primerange
    def aupton(terms):
      p = list(primerange(1, prime(terms+1)+1))
      return [p[n+1]**2-p[n]**2 for n in range(terms)]
    print(aupton(50)) # Michael S. Branicky, May 16 2021
  • Sage
    [nth_prime(n+1)^2 - nth_prime(n)^2 for n in (1..40)] # G. C. Greubel, May 19 2019
    

A133538 Sum of seventh powers of two consecutive primes.

Original entry on oeis.org

2315, 80312, 901668, 20310714, 82235688, 473087190, 1304210412, 4298697186, 20654701756, 44762490420, 122444491244, 289686151014, 466572884988, 778441731570, 1681334260300, 3663362624656, 5631394320840, 9203454441344, 15155831763714, 20142518677488
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=2315 because 2^7 + 3^7 = 2315.
		

Crossrefs

Programs

  • Magma
    [NthPrime(n)^7 + NthPrime(n+1)^7: n in [1..25]]; // Vincenzo Librandi, Aug 23 2018
  • Maple
    seq(add(ithprime(n+k)^7,k=0..1),n=1..20); # Muniru A Asiru, Aug 22 2018
  • Mathematica
    e = 7; Table[Prime[n]^e + Prime[n + 1]^e, {n, 1, 100}]
    Total/@Partition[Prime[Range[20]]^7,2,1] (* Harvey P. Dale, Oct 16 2014 *)
  • PARI
    a(n) = prime(n)^7 + prime(n+1)^7; \\ Michel Marcus, Aug 22 2018
    

Formula

a(n) = A092759(n) + A092759(n+1). - Michel Marcus, Nov 09 2013

A133534 Sum of third powers of two consecutive primes.

Original entry on oeis.org

35, 152, 468, 1674, 3528, 7110, 11772, 19026, 36556, 54180, 80444, 119574, 148428, 183330, 252700, 354256, 432360, 527744, 658674, 746928, 882056, 1064826, 1276756, 1617642, 1942974, 2123028, 2317770, 2520072, 2737926, 3491280
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=35 because 2^3+3^3=35.
		

Crossrefs

Programs

  • Mathematica
    a = 3; Table[Prime[n]^a + Prime[n + 1]^a, {n, 1, 100}]
    Total[#^3]&/@Partition[Prime[Range[50]],2,1] (* Harvey P. Dale, Jan 29 2021 *)

Formula

a(n) = A030078(n) + A030078(n+1). - Michel Marcus, Nov 09 2013

A133535 Sum of fourth powers of two consecutive primes.

Original entry on oeis.org

97, 706, 3026, 17042, 43202, 112082, 213842, 410162, 987122, 1630802, 2797682, 4699922, 6244562, 8298482, 12770162, 20007842, 25963202, 33996962, 45562802, 53809922, 67348322, 86408402, 110200562, 151271522, 192589682, 216611282
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=2^4+3^4=97.
		

Crossrefs

Programs

  • Mathematica
    a = 4; Table[Prime[n]^a + Prime[n + 1]^a, {n, 1, 100}]

Formula

a(n) = A030514(n) + A030514(n+1). - Michel Marcus, Nov 09 2013

A133536 Sum of fifth powers of two consecutive primes.

Original entry on oeis.org

275, 3368, 19932, 177858, 532344, 1791150, 3895956, 8912442, 26947492, 49140300, 97973108, 185200158, 262864644, 376353450, 647540500, 1133119792, 1559520600, 2194721408, 3154354458, 3877300944, 5150127992, 7016097042, 9523100092
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=2^5+3^5=275.
		

Crossrefs

Programs

  • Mathematica
    a = 5; Table[Prime[n]^a + Prime[n + 1]^a, {n, 1, 100}]

Formula

a(n) = A050997(n) + A050997(n+1). - Michel Marcus, Nov 09 2013

A133537 Sum of sixth powers of two consecutive primes.

Original entry on oeis.org

793, 16354, 133274, 1889210, 6598370, 28964378, 71183450, 195081770, 742859210, 1482327002, 3453230090, 7315830650, 11071467290, 17100578378, 32943576458, 64344894770, 93700908002, 141978756530, 218558666090, 279434510210
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=793 because 2^6+3^6=793.
		

Crossrefs

Programs

  • Mathematica
    a = 6; Table[Prime[n]^a + Prime[n + 1]^a, {n, 1, 100}]

Formula

a(n) = A030516(n) + A030516(n+1). - Michel Marcus, Nov 09 2013

A133539 Sum of third powers of five consecutive primes.

Original entry on oeis.org

1834, 4023, 8909, 15643, 27467, 50525, 78119, 123859, 185921, 253261, 332695, 451781, 606507, 764567, 985823, 1239911, 1480051, 1767711, 2112517, 2516723, 3071485, 3712769, 4312457, 4965713, 5555773, 6085997, 7104079, 8259443
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=1834 because 2^3+3^3+5^3+7^3+11^3=1834.
		

Crossrefs

Programs

  • Mathematica
    a = 3; Table[Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a + Prime[n + 3]^a + Prime[n + 4]^a, {n, 1, 100}]
    Total[#^3]&/@Partition[Prime[Range[40]],5,1] (* Harvey P. Dale, May 01 2013 *)

Formula

a(n) = A133525(n) + A030078(n+4). - Michel Marcus, Nov 09 2013

A133543 Sum of seventh powers of five consecutive primes.

Original entry on oeis.org

20391154, 83139543, 493476029, 1387269643, 4791271547, 22021660685, 49471526279, 143993064739, 337853466881, 606267252541, 1095640496695, 2242839022421, 4636558630107, 7584547192247, 13373440186463
Offset: 1

Views

Author

Artur Jasinski, Sep 14 2007

Keywords

Examples

			a(1)=20391154 because 2^7+3^7+5^7+7^7+11^7=20391154
		

Crossrefs

Programs

  • Mathematica
    a = 7; Table[Prime[n]^a + Prime[n + 1]^a + Prime[n + 2]^a + Prime[n + 3]^a + Prime[n + 4]^a, {n, 1, 100}]
    Total/@Partition[Prime[Range[20]]^7,5,1] (* Harvey P. Dale, Mar 05 2022 *)
Showing 1-10 of 22 results. Next