A304488 Numbers k where A304356(k)-A304358(k) changes sign.

17, 18, 19, 23, 24, 223, 224, 261, 263, 264, 385, 415, 417, 418, 442, 812, 815, 822, 823, 824, 826, 843, 846, 849, 850, 851, 875, 3877, 3879, 3887, 3907, 3968, 3971, 3973, 3975, 4247, 4249, 4269, 4270, 4327, 4394, 4399, 4802, 4804, 4806, 4809, 4810, 4812, 5072, 5078, 5087, 5088, 5095, 5426, 5427, 5483

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..565

Example

A304356(n)>A304358(n) for n=1..16, but A304356(17)=1039<A304358(17)=1129, so a(1)=17.

Maple

N:= 10^5:
P1:= select(isprime, [seq(i, i=1..N, 4)]):
P3:= select(isprime, [seq(i, i=3..N, 4)]):
A1:= select(isprime, P1[1..-3]+P1[2..-2]+P1[3..-1]):
A3:= select(isprime, P3[1..-3]+P3[2..-2]+P3[3..-1]):
M:= min(nops(A1), nops(A3)):
sg:= [seq(signum(A1[i]-A3[i]), i=1..M)]:
select(t -> sg[t]<>sg[t-1], [$2..M]);

Crossrefs

Cf. A304356, A304358

Sequence in context: A296757 A297287 A018822 * A043594 A043825 A043831

Adjacent sequences: A304485 A304486 A304487 * A304489 A304490 A304491

Keyword

nonn,look

Author

J. M. Bergot and Robert Israel, May 13 2018

Status

approved