A182177 Beginning with 0, smallest positive integer not yet in the sequence such that two adjacent digits of the sequence (also ignoring commas between terms) sum to a prime.

0, 2, 1, 4, 3, 8, 5, 6, 7, 41, 11, 12, 9, 20, 21, 14, 16, 50, 23, 25, 29, 43, 47, 49, 83, 85, 61, 65, 67, 411, 111, 112, 30, 32, 34, 38, 52, 56, 58, 92, 94, 70, 74, 76, 114, 98, 302, 116, 120, 202, 121, 123, 89, 203, 205, 207, 412, 125, 211, 129, 212, 141, 143, 214, 147, 414, 149, 216, 161, 165, 230, 232, 167, 416, 502, 303, 234, 305, 238, 307, 430, 250, 252, 320, 256, 503, 258, 321, 292, 323, 294, 325, 298, 329, 432, 341, 434, 343, 438, 347, 470, 349

Offset

1,2

Comments

A219250 is the analog of this sequence, replacing "sum" by "absolute difference". A219249 is the same analog for A182178. A219248 is the analog of A182175 and A219251 corresponds to A219110 = terms which do not occur in this sequence, i.e., the complement of its range. - M. F. Hasler, Apr 12 2013

Links

Table of n, a(n) for n=1..102.

Example

41 appears after 7 because 7+4 is prime and 4+1 is prime, and no other number less than 41 (not already in the sequence) satisfies this property. Example: 11 does not directly follow 7 since 7+1 is not prime.

Prog

(PARI) A182177_vec={(n, a=[0], u=0)->while(#a<n, u+=1<<a[#a]; for(t=a[1]+1, 9e9, bittest(u, t)&next; my(d=concat(a[#a]%10, digits(t))); for(i=2, #d, isprime(d[i-1]+d[i])||next(2)); a=concat(a, t); break)); a} \\ M. F. Hasler, Apr 11 2013

Crossrefs

Cf. A182175.

Sequence in context: A074987 A294096 A128280 * A281878 A106625 A275902

Adjacent sequences: A182174 A182175 A182176 * A182178 A182179 A182180

Keyword

nonn,base,easy

Author

Jim Nastos and Eric Angelini, Apr 16 2012

Status

approved