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.

A051318 Euclid-Mullin sequence (A000945) with initial value a(1)=43 instead of a(1)=2.

Original entry on oeis.org

43, 2, 3, 7, 13, 53, 5, 6221671, 38709183810571, 139, 2801, 11, 17, 5471, 52662739, 23003, 30693651606209, 37, 1741, 1313797957, 887, 71, 7127, 109, 23, 97, 159227, 643679794963466223081509857, 103, 1079990819, 9539, 3143065813, 29, 3847, 89, 19, 577, 223
Offset: 1

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Keywords

Examples

			Product of first 28 terms +1 is 210102491806660945690525037461258737117339882568590700172677987135969766432980375 44232424110733238484973548134278212304532631, which is divisible by 103. Hence a(29)=103.
		

Crossrefs

Agrees with A000945 from 5th term. Cf. A000946, A005265, A005266.

Programs

  • Mathematica
    a[1]=43; a[n_] := First[ Flatten[ FactorInteger[ 1+Product[ a[ j ], {j, n-1} ] ] ] ]; Array[a, 15]
  • PARI
    spf(n)=factor(n)[1, 1]
    first(m)={my(v=vector(m),i,t=43);v[1]=43;for(i=2,m,v[i]=spf(t+1);t*=v[i];);v;} /* Anders Hellström, Jul 19 2015 */

Extensions

a(31)-a(38) from Robert Price, Jul 19 2015