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.

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A319353 Filter sequence combining weights of partitions with Heinz-numbers equal to the proper divisors of n.

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 4, 5, 6, 2, 7, 2, 8, 9, 10, 2, 11, 2, 11, 12, 13, 2, 14, 15, 16, 12, 17, 2, 18, 2, 11, 19, 20, 21, 22, 2, 23, 24, 18, 2, 25, 2, 26, 27, 28, 2, 29, 30, 31, 32, 33, 2, 25, 34, 25, 35, 36, 2, 37, 2, 38, 39, 40, 41, 42, 2, 43, 44, 45, 2, 37, 2, 46, 47, 48, 49, 50, 2, 51, 52, 53, 2, 54, 55, 56, 57, 42, 2, 58, 59, 60, 61, 62, 63, 37, 2, 64, 65
Offset: 1

Views

Author

Antti Karttunen, Sep 17 2018

Keywords

Comments

Restricted growth sequence transform of A319352.
For all i, j:
a(i) = a(j) => A301855(i) = A301855(j).
a(i) = a(j) => A304793(i) = A304793(j).

Crossrefs

Programs

  • PARI
    up_to = 65537;
    rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
    A056239(n) = { my(f); if(1==n, 0, f=factor(n); sum(i=1, #f~, f[i,2] * primepi(f[i,1]))); }
    A319352(n) = { my(m=1); fordiv(n, d, if(dA056239(d)))); (m); };
    v319353 = rgs_transform(vector(up_to,n,A319352(n)));
    A319353(n) = v319353[n];

A319692 a(n) = Product_{d|n, dA001414(d)), where A001414(d) gives the sum of prime factors of d, with repetition.

Original entry on oeis.org

1, 2, 2, 10, 2, 70, 2, 110, 14, 130, 2, 10010, 2, 190, 182, 1870, 2, 15470, 2, 27170, 266, 370, 2, 3233230, 26, 430, 238, 60610, 2, 5169710, 2, 43010, 518, 610, 494, 74364290, 2, 710, 602, 13394810, 2, 15543710, 2, 175010, 71162, 890, 2, 2156564410, 38, 76570, 854, 250690, 2, 10318490, 962, 38123690, 994, 1130, 2, 971341981610, 2, 1310, 140182, 1333310, 1118
Offset: 1

Views

Author

Antti Karttunen, Oct 02 2018

Keywords

Crossrefs

Cf. A001414, A319693 (rgs-transform).
Cf. also A319352.

Programs

Formula

a(n) = Product_{d|n, dA000040(1+A001414(d)).
For all n >= 1:
A001221(a(n)) = A305611(n).
Showing 1-2 of 2 results.