A088365 - OEIS

A088365

Local maxima of A053707 (first differences of A025475, powers of a prime but not prime).

4, 9, 17, 40, 74, 54, 151, 120, 307, 312, 199, 408, 356, 424, 912, 1032, 1217, 840, 1872, 423, 1608, 2518, 1588, 1920, 1230, 2112, 3713, 1560, 5208, 2832, 3952, 2872, 3192, 3288, 3432, 8400, 5738, 4080, 4272, 4512, 6288, 8280, 8520, 5232, 5352, 3672, 8892

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

A053707(k) for k = 1 is a term iff A053707(k) >= A053707(k+1); A053707(k) for k > 1 is a term iff A053707(k-1) < A053707(k) and A053707(k) >= A053707(k+1).

A088366 gives the corresponding indices. Local minima of A053707 are in A088363.

LINKS

Table of n, a(n) for n=1..47.

EXAMPLE

The first six terms of A053707 are 3,4,1,7,9,2, hence A053707(2) = 4 is the first and A053707(5) = 9 is the second local maximum of A053707.

PROG

(PARI) {m=1; k=0; for(n=2, 250000, if(matsize(factor(n))[1]==1&&factor(n)[1, 2]>1, d=n-m; if((k<2||b<c)&&(!k<1&&d<=c), print1(c, ", ")); k++; m=n; b=c; c=d))}

CROSSREFS

Cf. A025475, A053707, A088366, A088363.

Sequence in context: A130785 A226310 A008236 * A139468 A127081 A162719

Adjacent sequences: A088362 A088363 A088364 * A088366 A088367 A088368

KEYWORD

nonn

AUTHOR

Klaus Brockhaus, Sep 27 2003

STATUS

approved