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A308274 Total number of nodes summed over all lattice paths from (0,0) to (n,n) that do not go above the diagonal x=y and consist of steps (h,v) with h, v prime or one. 3
1, 2, 5, 15, 47, 147, 469, 1531, 5076, 17014, 57537, 196043, 671980, 2314592, 8005266, 27784114, 96720440, 337572161, 1180869043, 4139120434, 14534125630, 51116699820, 180036470572, 634925138580, 2241803318605, 7923931456994, 28035799832528, 99284104334614 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..600

Wikipedia, Counting lattice paths

MAPLE

b:= proc(x, y) option remember; `if`(y=0, [1$2], (p-> p+[0, p[1]])(

      add(add(`if`((h=1 or isprime(h)) and (v=1 or isprime(v)) and

      (x-h<=y-v), b(x-h, y-v), 0), v=1..y), h=1..x)))

    end:

a:= n-> b(n$2)[2]:

seq(a(n), n=0..30);

CROSSREFS

Cf. A000040, A008578, A308241, A308273.

Sequence in context: A148361 A148362 A143094 * A058495 A287275 A151280

Adjacent sequences:  A308271 A308272 A308273 * A308275 A308276 A308277

KEYWORD

nonn

AUTHOR

Alois P. Heinz, May 17 2019

STATUS

approved

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Last modified November 21 06:00 EST 2019. Contains 329350 sequences. (Running on oeis4.)