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.

A074741 Sum of squares of gaps between consecutive primes.

Original entry on oeis.org

1, 5, 9, 25, 29, 45, 49, 65, 101, 105, 141, 157, 161, 177, 213, 249, 253, 289, 305, 309, 345, 361, 397, 461, 477, 481, 497, 501, 517, 713, 729, 765, 769, 869, 873, 909, 945, 961, 997, 1033, 1037, 1137, 1141, 1157, 1161, 1305, 1449, 1465, 1469, 1485, 1521
Offset: 1

Views

Author

Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Sep 05 2002

Keywords

References

  • R. K. Guy, Unsolved Problems in Number Theory, Springer-Verlag, New York, Heidelberg, 1994, problem A8.

Crossrefs

Partial sums of A076821. - Michel Marcus, May 26 2018
Cf. A001223.

Programs

  • Maple
    with(numtheory): a := proc(n) option remember: if (n=1) then RETURN(1) else RETURN(a(n-1)+(ithprime(n+1)-ithprime(n))^2) fi: end:
  • Mathematica
    Rest[FoldList[Plus, 0, (#[[2]] - #[[1]])^2 & /@ Partition[Prime[Range[100]], 2, 1]]]
    nn=60;With[{dsp=Differences[Prime[Range[nn+1]]]^2},Table[Total[Take[ dsp,n]],{n,nn}]] (* Harvey P. Dale, Nov 30 2011 *)
    Accumulate[Differences[Prime[Range[60]]]^2] (* Harvey P. Dale, May 08 2015 *)
  • PARI
    a(n) = sum(k=1, n, (prime(k+1) - prime(k))^2); \\ Michel Marcus, May 26 2018
    
  • Python
    from sympy import nextprime
    from itertools import islice, accumulate
    def gen():
        p, q = 2, 3
        while True:
            r = (q - p) ** 2
            yield r
            p, q = q, nextprime(q)
    print(list(accumulate(islice(gen(), 51)))) # Adrienne Leonardo, Dec 18 2024

Formula

a(n) = Sum_{k=1..n} (prime(k+1)-prime(k))^2 = Sum_{k=1..n} A001223(k)^2.
Asymptotic expressions: D. R. Heath-Brown's conjecture: Sum_{prime(n)<=N} (prime(n)-prime(n-1))^2 ~ 2*N*log(N). Marek Wolf's conjecture: Sum_{prime(n)A000720(n).