A255423 The least number k > A255334(n) for which A000203(k) = A000203(A255334(n)) and A007947(k) = A007947(A255334(n)), where A000203 gives the sum of divisors, and A007947 gives the squarefree kernel of n.

2058, 10290, 22638, 26754, 34986, 39102, 47334, 51450, 59682, 52728, 63798, 76146, 84378, 88494, 96726, 109074, 113190, 121422, 125538, 133770, 137886, 146118, 150234, 162582, 170814, 174930, 183162, 195510, 199626, 207858, 211974, 220206, 224322, 232554, 236670, 249018, 257250, 261366, 269598, 281946, 286062, 294294

Offset: 1

Author

Antti Karttunen, Apr 06 2015

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..6589

Crossrefs

Cf. A000203, A007947, A255334.

Cf. also A255335 (same sequence sorted into ascending order), A255424 (squarefree kernel of a(n)), A255426 (same terms with but with their squarefree kernel divided out of them).

Programs

PARI

A007947(n) = factorback(factorint(n)[, 1]);
nextone(n) = { if(!n,return(0)); my(r=A007947(n), s=sigma(n), k=n+r); while(kA007947(k) == r), return(k), k = k+r)); return(0); };
i=0; for(n=1, 2^25, k = nextone(n); if(k, i++; write("b255423.txt", i, " ", k))); \\ Andrew Lelechenko, May 09 2014

Formula

a(n) = A255424(n) * A255426(n).