A373172 a(1) = 1; for n >= 2, a(n) = noz(a(n-1) + 4*n - 3), where noz(n) = A004719(n).

1, 6, 15, 28, 45, 66, 91, 12, 45, 82, 123, 168, 217, 27, 84, 145, 21, 9, 82, 159, 24, 19, 18, 111, 28, 129, 234, 343, 456, 573, 694, 819, 948, 181, 318, 459, 64, 213, 366, 523, 684, 849, 118, 291, 468, 649, 834, 123, 316, 513, 714, 919, 1128, 1341, 1558, 1779

Offset: 1

Author

Paolo Xausa, May 28 2024

Keywords

• nonn
• base
• easy

Comments

Zeroless analog of the positive hexagonal numbers.

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000

Crossrefs

Row n = 6 of A373169.

Cf. A000384, A004719, A243658, A370812, A373171.

Programs

Mathematica

noz[n_] := FromDigits[DeleteCases[IntegerDigits[n], 0]];
Block[{n = 1}, NestList[noz[++n*4 - 3 + #] &, 1, 100]]
nxt[{n_,a_}]:={n+1,FromDigits[DeleteCases[IntegerDigits[a+4n+1],0]]}; NestList[nxt,{1,1},60][[;;,2]] (* Harvey P. Dale, Jul 08 2024 *)

PARI

noz(n) = fromdigits(select(sign, digits(n))); \\ A004719
lista(nn) = my(va=vector(nn)); for (n=1, nn, va[n] = if (n==1, 1, noz(va[n-1] + 4*n - 3))); va; \\ Michel Marcus, Jun 03 2024