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.

A235725 Values k(i) such that k(i) + k(i+3) = k(i+1) + k(i+2), where k(i) is A022885(i).

Original entry on oeis.org

5, 353, 541, 853, 2341, 4217, 4229, 8219, 10663, 11047, 13591, 18593, 21577, 28387, 30181, 34457, 37853, 52021, 55333, 57203, 75389, 84431, 93229, 110603, 120811, 147451, 153499, 162907, 166357, 176797, 179581, 219953, 243671, 246203, 307253, 342037, 359701
Offset: 1

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Author

Vladimir Shevelev, Jan 15 2014

Keywords

Examples

			Four consecutive Kimberling primes(A022885), beginning with 5 are 5,7,11,13. Since 5+13 = 7+11, then 5 is in the sequence; four consecutive Kimberling primes, beginning with 7 are 7,11,13,23. Since 7+23 is not equal to 11+13, then 7 is not in the sequence.
		

Crossrefs

Cf. A022885.

Programs

  • Mathematica
    Nest[Map[#[[1]]&,Select[Partition[#,4,1],#[[1]]+#[[4]]==#[[2]]+#[[3]]&]]&,Prime[Range[5000]],2]
  • PARI
    isA022885(p) = {my(k = primepi(p)); (p == prime(k)) && ((prime(k) + prime(k+3)) == (prime(k+1) + prime(k+2)));}
    lista(nn) = {prm = primes(nn); vkp = select(p->isA022885(p), prm); for(n=1, #vkp-3, if ((vkp[n] + vkp[n+3]) == (vkp[n+1] + vkp[n+2]), print1(vkp[n], ", ")););}  \\ Michel Marcus, Jan 15 2014

Extensions

a(5)-a(37) from Giovanni Resta, Jan 15 2014