A093497 Beginning with 6, numbers such that every partial concatenation has the same prime signature p*q.

6, 2, 2, 7, 7, 1, 1, 8, 7, 3, 3, 9, 1, 3, 13, 3, 7, 3, 11, 3, 7, 3, 3, 15, 9, 9, 17, 3, 102, 3, 22, 7, 7, 51, 3, 7, 26, 43, 9, 39, 8, 1, 29, 7, 39, 53, 7, 59, 81, 39, 41, 1, 11, 47, 23, 39, 13, 13, 89, 15, 101, 7, 17, 21, 7, 3, 81, 51, 23, 31, 23, 1, 3, 3, 39

Offset

1,1

Links

Table of n, a(n) for n=1..75.

Dario Alpern, Factorization using the Elliptic Curve Method

Example

62, 622, 6227, 62277, etc. have the same prime signature p*q.

Prog

(PARI) digs(k) = if (k, digits(k), [0]);
isok(vd, k) = {newv = concat(vd, digs(k)); val = fromdigits(newv); (bigomega(val) == 2) && (omega(val) == 2); }
fnew(vd) = {k = 0; while (! isok(vd, k), k++); k; }
lista(nn) = {k = 6; v = [k]; vd = digs(k); print1(v[1], ", "); for (n=2, nn, k = fnew(vd); print1(k, ", "); v = concat(v, k); vd = concat(vd, digs(k)); ); } \\ Michel Marcus, Jan 21 2017

Crossrefs

Cf. A006881.

Sequence in context: A259838 A256576 A201674 * A092138 A138995 A010133

Adjacent sequences: A093494 A093495 A093496 * A093498 A093499 A093500

Keyword

nonn,base

Author

Amarnath Murthy, Apr 17 2004

Extensions

More terms from David Wasserman, Jun 07 2007

Edited and a(69)-a(85) moved to comments by Michel Marcus, Jan 21 2017

More terms from Jinyuan Wang, Jul 09 2020

Status

approved