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.

A370137 Sums of three primorials > 1.

Original entry on oeis.org

6, 10, 14, 18, 34, 38, 42, 62, 66, 90, 214, 218, 222, 242, 246, 270, 422, 426, 450, 630, 2314, 2318, 2322, 2342, 2346, 2370, 2522, 2526, 2550, 2730, 4622, 4626, 4650, 4830, 6930, 30034, 30038, 30042, 30062, 30066, 30090, 30242, 30246, 30270, 30450, 32342, 32346, 32370, 32550, 34650, 60062, 60066, 60090, 60270, 62370, 90090
Offset: 1

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Author

Antti Karttunen, Mar 09 2024

Keywords

Examples

			6 = A002110(1) + A002110(1) + A002110(1) = 2+2+2.
10 = A002110(2) + A002110(1) + A002110(1) = 6+2+2.
14 = A002110(2) + A002110(2) + A002110(1) = 6+6+2.
18 = A002110(2) + A002110(2) + A002110(2) = 6+6+6.
38 = A002110(3) + A002110(2) + A002110(1) = 30+6+2.
		

Crossrefs

Subsequence of A370133.
Cf. also A370134.

Programs

  • Mathematica
    nn = 6; MapIndexed[Set[P[First[#2] - 1], #1] &, FoldList[Times, 1, Prime@ Range[nn]]]; Table[P[i] + P[j] + P[k], {i, nn}, {j, i}, {k, j}] // Flatten (* Michael De Vlieger, Mar 09 2024 *)
  • PARI
    up_to = 15180;
    A002110(n) = prod(i=1,n,prime(i));
    A370137list(up_to) = { my(v = vector(up_to), i=0); for(x=1,oo, for(y=1,x, for(z=1,y, i++; if(i > up_to, return(v)); v[i] = A002110(x)+A002110(y)+A002110(z)))); (v); };
    v370137 = A370137list(up_to);
    A370137(n) = v370137[n];

Formula

For n > 1, A276150(a(n)) = 3.
For n > 1, A276086(a(n)) = A369979(n).