A243937 -id:A243937 - cp's OEIS frontend

A242060 Lpf_3(A242058(n)-3), where lpf_3(n) = lpf(n/3^t) (cf. A020639) such that 3^t (t>=0) is the maximal power of 3 which divides n.

1, 5, 1, 11, 5, 17, 7, 1, 29, 5, 13, 41, 5, 7, 17, 5, 19, 59, 5, 23, 71, 5, 7, 1, 5, 29, 7, 5, 11, 101, 5, 107, 37, 5, 7, 11, 5, 43, 5, 137, 5, 7, 149, 5, 7, 5, 13, 19, 5, 59, 179, 5, 7, 191, 5, 197, 5, 11, 5, 7, 13, 5, 227, 7, 5, 79, 239, 1, 5, 13, 83, 5, 7

Offset: 1

Vladimir Shevelev, Aug 13 2014

nonn

An analog of A242034. Records are lesser numbers of twin primes.

Cf. A245024, A243937, A242057, A242058, A242059, A242033, A242034.

lpf[n_]:=lpf[n]=First[First[FactorInteger[n]]];
lpf3[n_]:=lpf3[n]=If[#==1,1,lpf[#]]&[n/3^IntegerExponent[n,3]]
Map[lpf3[#-3]&,Select[Range[4,300,2],lpf3[#-1]>lpf3[#-3]&]](* Peter J. C. Moses, Aug 13 2014 *)

More terms from Peter J. C. Moses, Aug 13 2014

A245272 Composite terms in sequence {A245024(n)-3}.

Original entry on oeis.org

25, 49, 55, 85, 91, 115, 121, 133, 143, 145, 169, 175, 187, 203, 205, 217, 235, 247, 253, 259, 265, 289, 295, 299, 301, 319, 323, 325, 341, 343, 355, 361, 385, 391, 403, 413, 415, 427, 445, 451, 469, 473, 475, 481, 493, 505, 511, 517, 529, 533, 535, 551, 553

Offset: 1

Vladimir Shevelev, Jul 16 2014

nonn

See comment in A245024.

The sequence contains all squares of primes more than 3. Indeed, since for such primes lpf(p^2+2)=3, then p^2+3 is in A245024.

Cf. A245024, A243937.

More terms from Peter J. C. Moses, Jul 16 2014

cp's OEIS Frontend

A242060 Lpf_3(A242058(n)-3), where lpf_3(n) = lpf(n/3^t) (cf. A020639) such that 3^t (t>=0) is the maximal power of 3 which divides n.

Views

Author

Keywords

Comments

Crossrefs

Programs

Mathematica

Extensions