A297150 Let b(k) denote A292081(k); the sequence lists numbers b(2n) where for all m > n, b(2m) > b(2n).

35, 65, 95, 115, 155, 185, 215, 235, 265, 305, 335, 365, 395, 415, 445, 485, 515, 545, 565, 635, 655, 695, 755, 785, 815, 835, 865, 905, 965, 995, 1055, 1115, 1145, 1165, 1205, 1255, 1285, 1315, 1355, 1385, 1415, 1465, 1535, 1565, 1585, 1655, 1685, 1745, 1765, 1795, 1835, 1865, 1895, 1915, 1945, 1985

Offset

1,1

Comments

This is also an ascending subsequence of the even-indexed terms of A056240(2n) (of which A292081 is a subsequence). For n >= 1, a(n) is a semiprime of the form a(n)=5*A049591(n), and the index m in A056240 of any term in this sequence belongs to the sequence of even numbers m such that m-5 is prime and m-3 is not prime (A297925). See A297925 for explanation.

Links

Vincenzo Librandi, Table of n, a(n) for n = 1..1690

Formula

a(n) = 5*A049591(n) = A056240(A297925(n)).

Example

a(1)=5*A049591(1)=5*7=35. Also A056240(A297925(1))=A056240(12)=35.
a(17)=5*A049591(17)=5*103=515. Also A056240(A297925(17))=A056240(108)=515.

Mathematica

5 Select[Prime[Range[3, 100]], ! PrimeQ[(# + 2)] &] (* Vincenzo Librandi, Nov 12 2018 *)

Prog

(Magma) [5*p: p in PrimesInInterval(3, 500) | not IsPrime(p + 2)]; // Vincenzo Librandi, Nov 12 2018

Crossrefs

Similar to A288313.

Cf. A292081, A288313, A056240, A049591, A297925.

Sequence in context: A338008 A331378 A331384 * A292081 A162832 A224485

Adjacent sequences: A297147 A297148 A297149 * A297151 A297152 A297153

Keyword

nonn

Author

David James Sycamore, Dec 26 2017

Status

approved